Merge bitcoin/bitcoin#27361: guix: use python-minimal (3.9)

d0e571e guix: use python-minimal (3.9) (fanquake)

Pull request description:

  This further minifies the Guix release build environment.

ACKs for top commit:
  TheCharlatan:
    ACK d0e571e
  hebasto:
    ACK d0e571e

Tree-SHA512: 0a8aa9ae861107f106c3b9c41f78ffbaf0e71e3c61f6d96e5c82415b4570b8ac85d6578d37cd0df0ec315c1c9f35fc90b281f139271ccfd15a1495ba76166789

Author: fanquake

contrib/guix/manifest.scm

@@ -598,7 +598,7 @@ inspecting signatures in Mach-O binaries.")
         gcc-toolchain-10
         (list gcc-toolchain-10 "static")
         ;; Scripting
-        python-3
+        python-minimal ;; (3.9)
         ;; Git
         git-minimal
         ;; Tests