gnu: marble-qt: Fix Git source URL.

The package failed to build with:
fatal: remote error: Please use the https: protocol to connect to anongit

Fix the protocol & follow the subsequent HTTP redirection.

* gnu/packages/geo.scm (marble-qt)[source]: Fix upstream URL.

gnu/packages/geo.scm

@@ -2435,7 +2435,7 @@ using third-party geocoders and other data sources.")
        (origin
          (method git-fetch)
          (uri (git-reference
-               (url "git://anongit.kde.org/marble")
+               (url "https://invent.kde.org/education/marble.git/")
                (commit commit)))
          (sha256
           (base32