gnu: emacs-fill-column-indicator: Don't use unstable tarball.

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

gnu/packages/emacs-xyz.scm

@@ -2229,13 +2229,13 @@ keep pressing the key until it selects what you want.  There's also
     (version "1.89")
     (source
      (origin
-       (method url-fetch)
-       (uri (string-append "https://github.com/alpaker/Fill-Column-Indicator"
-                           "/archive/v" version ".tar.gz"))
-       (file-name (string-append name "-" version ".tar.gz"))
+       (method git-fetch)
+       (uri (git-reference
+             (url "https://github.com/alpaker/Fill-Column-Indicator.git")
+             (commit (string-append "v" version))))
+       (file-name (git-file-name name version))
        (sha256
-        (base32
-         "09ab01np14bdcsr38xf95kpnvxzqr46mdjmphg3pigwnx39a3jvg"))))
+        (base32 "010kf8jsly74y7m6mmkn1h6y205kz23zphs50zgy2nag2p88rz9y"))))
     (build-system emacs-build-system)
     (home-page "https://www.emacswiki.org/emacs/FillColumnIndicator")
     (synopsis "Graphically indicate the fill column")