Use default guix channel for test

Author: declantsien

.github/workflows/test.yml

@@ -23,14 +23,7 @@ jobs:
         with:
           channels: |-
             (list (channel
-                   (name 'guix)
-                   (url "https://github.com/declantsien/guix")
-                   (branch "master")
-                   (introduction
-                    (make-channel-introduction
-                     "9edb3f66fd807b096b48283debdcddccfea34bad"
-                     (openpgp-fingerprint
-                      "BBB0 2DDF 2CEA F6A8 0D1D  E643 A2A0 6DF2 A33A 54FA"))))
+                   (inherit %default-guix-channel))
                   (channel
                    (name 'rustup)
                    (url "https://github.com/declantsien/guix-rustup")