gnu: emacs-gitpatch: Don't use unstable tarball.

* gnu/packages/emacs-xyz.scm (emacs-gitpatch)[source]: Use GIT-FETCH and
GIT-FILE-NAME.

gnu/packages/emacs-xyz.scm

@@ -7748,13 +7748,13 @@ internally.")
     (version "0.5.0")
     (source
      (origin
-       (method url-fetch)
-       (uri (string-append "https://github.com/tumashu/gitpatch/archive/"
-                           "v" version ".tar.gz"))
-       (file-name (string-append name "-" version ".tar.gz"))
+       (method git-fetch)
+       (uri (git-reference
+             (url "https://github.com/tumashu/gitpatch.git")
+             (commit (string-append "v" version))))
+       (file-name (git-file-name name version))
        (sha256
-        (base32
-         "1yj6pmic541lcnscjin300k380qp9xdfprs55xg1q57jrkq6f6k7"))))
+        (base32 "1jj12pjwza6cq8a3kr8nqnmm3vxs0wam8h983irry4xr4ifywsn4"))))
     (build-system emacs-build-system)
     (home-page "https://github.com/tumashu/gitpatch")
     (synopsis "Mail git patch from Emacs")