Bump MailKit from 2.1.3 to 2.4.1

[dependabot-preview]

Bumps MailKit from 2.1.3 to 2.4.1.

Changelog

Sourced from MailKit's changelog.

MailKit 2.4.1 (2019-11-10)

• Don't use PublicSign on non-Windows NT machines when building.
• Work-around broken BODYSTRUCTUREs with () as a message/rfc822 body token.
  (issue #944)
• Added work-around for an Exchange bug that forgets to quote folder names containing tabs.
  (issue #945)
• Moved the SmtpDataFilter into the public API and updated the FAQ to show how to
  use it when writing messages into an IIS "pickup directory".
  (issue #948)

MailKit 2.4.0 (2019-11-02)

• Added work-around for IMAP ENVELOPE responses that do not include an In-Reply-To token.
  (issue #932)
• Dropped support for WindowsPhone/Universal v8.1.
• Added a net48 assembly to the NuGet package which supports TLS v1.3.
• Added work-around for Yandex IMAP servers to disconnect immediately upon * BYE.
  (issue #938)
• Fixed ImapClient.Idle() and IdleAsync().
  (issue #942)
• Added work-around for Lotus Domino where it adds extra ()'s around some FETCH items.
  (issue #943)

MailKit 2.3.2 (2019-10-12)

• Fixed trimming delimeters from the end of IMAP folder names.
• Fixed fetching of IMAP PreviewText when message bodies do not contain any text parts.
• Fixed Pop3Client to never emit Authenticated events w/ null messages.
• Dropped SslProtocols.Tls (aka TLSv1.0) from the default SslProtocols used by IMAP, POP3
  and SMTP clients. To override this behavior, use the client.SslProtocols property
  to set the preferred SslProtocol(s).
• Fixed ImapFolder.Search(string query) to properly encode the query string when the query
  contains unicode characters.
• If an IMAP SEARCH fails due to BADCHARSET, retry the search query after flattening the
  query strings into US-ASCII. This may fix issues such as
  issue #808.
• Added work-arounds for Exchange IMAP bugs causing it to send mal-formed body-fld-dsp
  parameters. (issue #919)
• Go back to only using the BDAT command when the user is sending BINARYMIME in the SmtpClient.
  (issue #921)

MailKit 2.3.1 (2019-09-08)

• Fixed SmtpClient.Send*() to make sure never to add an extra CRLF sequence to the end of
  messages when sending via the DATA command.
  (issue #895)
• Added assemblies for net46 and net47 to the NuGet package.

MailKit 2.3.0 (2019-08-24)

... (truncated)

Commits

• 70292e2 bumped version to 2.4.1
• aec28ff Move the SmtpDataFilter into the public API.
• a8b8dac Added work-around for an Exchange bug that forgets to quote folder names cont...
• 003277f Work-around broken BODYSTRUCTUREs with () as a message/rfc822 body token
• edae32b Don't use PublicSign on non-Windows NT machines when building.
• 3c9be50 updated samples
• 3ac8f2e Update ReleaseNotes.md
• 230001f bumped version to 2.4.0
• fd696bf minor fixup for restoring the ImapStream's ReadTimeout
• d8778c2 Redesigned IMAP IDLE support to be much simpler
• Additional commits viewable in compare view

Dependabot will resolve any conflicts with this PR as long as you don't alter it yourself. You can also trigger a rebase manually by commenting @dependabot rebase.

---

Dependabot commands and options

You can trigger Dependabot actions by commenting on this PR:

• @dependabot rebase will rebase this PR
• @dependabot recreate will recreate this PR, overwriting any edits that have been made to it
• @dependabot merge will merge this PR after your CI passes on it
• @dependabot squash and merge will squash and merge this PR after your CI passes on it
• @dependabot cancel merge will cancel a previously requested merge and block automerging
• @dependabot reopen will reopen this PR if it is closed
• @dependabot close will close this PR and stop Dependabot recreating it. You can achieve the same result by closing it manually
• @dependabot ignore this major version will close this PR and stop Dependabot creating any more for this major version (unless you reopen the PR or upgrade to it yourself)
• @dependabot ignore this minor version will close this PR and stop Dependabot creating any more for this minor version (unless you reopen the PR or upgrade to it yourself)
• @dependabot ignore this dependency will close this PR and stop Dependabot creating any more for this dependency (unless you reopen the PR or upgrade to it yourself)
• @dependabot use these labels will set the current labels as the default for future PRs for this repo and language
• @dependabot use these reviewers will set the current reviewers as the default for future PRs for this repo and language
• @dependabot use these assignees will set the current assignees as the default for future PRs for this repo and language
• @dependabot use this milestone will set the current milestone as the default for future PRs for this repo and language
• @dependabot badge me will comment on this PR with code to add a "Dependabot enabled" badge to your readme

Additionally, you can set the following in your Dependabot dashboard:

• Update frequency (including time of day and day of week)
• Pull request limits (per update run and/or open at any time)
• Automerge options (never/patch/minor, and dev/runtime dependencies)
• Out-of-range updates (receive only lockfile updates, if desired)
• Security updates (receive only security updates, if desired)

[coveralls]

Pull Request Test Coverage Report for Build 7gw3054d4pjrd425

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+1.6%) to 72.949%

---

Totals
Change from base Build pna9ayfnnd71yjf8:	1.6%
Covered Lines:	329
Relevant Lines:	451

---

💛 - Coveralls