Python 3.12 compatibility fixes for shell history parsing and history filtering

[olucasfracaro]

This PR fixes the remaining Python 3.12 issues I found while running the test suite locally.

What was fixed

• Fish/Tcsh history parsing

  • Updated get_history() in fish.py and tcsh.py to read history via io.open(...).readlines(), matching current test fixtures and avoiding empty history results in tests.
  • Kept safe error handling for missing/unreadable history files.

• History filtering in utils.py

  • Adjusted get_valid_history_without_current() filtering to:
    • keep valid Unicode history entries (e.g. café ô)
    • still exclude invalid commands (e.g. nocommand x)
    • continue excluding current command and alias-invocation lines as expected

Validation

Ran locally on Python 3.12.3:

• pytest tests/shells -q ✅
• full suite: 1887 passed, 62 skipped ✅

Related

• Related to ongoing Python 3.12 support work in support:support for Python 3.12+ #1569.