Merge bitcoin/bitcoin#35810: guix: Drop unused (guix licenses) import from manifest_build.scm

a92e934 guix: Drop unused `(guix licenses)` import from `manifest_build.scm` (Hennadii Stepanov)

Pull request description:

  This was overlooked in bitcoin/bitcoin#34948.

ACKs for top commit:
  fanquake:
    ACK a92e934

Tree-SHA512: ab1ff63b49da104b21c4731ea06d3a4db009712be7c50f907cd46d0ad2936f7a236915bbe436801f02ea32bd781dfb5f38d349dda0a99a563701bef1089f35a6

Author: fanquake

contrib/guix/manifest_build.scm

@@ -14,7 +14,6 @@
              (guix download)
              (guix gexp)
              (guix git-download)
-             ((guix licenses) #:prefix license:)
              (guix packages)
              ((guix utils) #:select (substitute-keyword-arguments)))