gnu: emacs-go-mode: Use release tag.

* gnu/packages/emacs-xyz.scm (emacs-go-mode)
[source]: Use the release tag, now that it's available.

Change-Id: I11e93a06a49e066cbcd4ee3f96fb4d4cfc25302f

gnu/packages/emacs-xyz.scm

@@ -6218,9 +6218,6 @@ current match, total matches and exit status.
       (license license:gpl3+))))
 
 (define-public emacs-go-mode
-  ;; XXX: Upstream did not tag last release.  The commit below matches version
-  ;; bump.
-  (let ((commit "3273fcece5d9ab7edd4f15b2d6bce61f4e5a0666"))
   (package
     (name "emacs-go-mode")
     (version "1.6.0")
@@ -6228,7 +6225,7 @@ current match, total matches and exit status.
               (method git-fetch)
               (uri (git-reference
                     (url "https://github.com/dominikh/go-mode.el")
-                      (commit commit)))
+                    (commit (string-append "v" version))))
               (file-name (git-file-name name version))
               (sha256
                (base32
@@ -6257,7 +6254,7 @@ current match, total matches and exit status.
     (description
      "This package provides go-mode, an Emacs mode for working with software
 written in the Go programming language.")
-      (license license:bsd-3))))
+    (license license:bsd-3)))
 
 (define-public emacs-google-maps
   ;; There has been no new release tag since 2013.