gnu: emacs-mu4e-alert: Don't use unstable tarball.

* gnu/packages/emacs-xyz.scm (emacs-mu4e-alert)[source]: Use GIT-FETCH and
GIT-FILE-NAME.

gnu/packages/emacs-xyz.scm

@@ -6078,14 +6078,13 @@ is, in effect, a (typically) noncontiguous set of text.")
     (version "1.0")
     (source
      (origin
-       (method url-fetch)
-       (uri (string-append
-             "https://github.com/iqbalansari/mu4e-alert/archive/v"
-             version ".tar.gz"))
-       (file-name (string-append name "-" version ".tar.gz"))
+       (method git-fetch)
+       (uri (git-reference
+             (url "https://github.com/iqbalansari/mu4e-alert.git")
+             (commit (string-append "v" version))))
+       (file-name (git-file-name name version))
        (sha256
-        (base32
-         "07qc834qnxn8xi4bw5nawj8g91bmkzw0r0vahkgysp7r9xrf57gj"))))
+        (base32 "1nvsfbfsma59ilf7c3vjngnmx3aapwvvvaafdy5szm5r6lkicqvg"))))
     (build-system emacs-build-system)
     (propagated-inputs
      `(("emacs-alert" ,emacs-alert)