Add --tags argument to git fetch

Should resolve flakiness where a manual `git fetch --tags` is sometimes
needed inside the `kobo-docker` directory to fix the following:

    error: pathspec '<tag>' did not match any file(s) known to git

helpers/setup.py

@@ -87,7 +87,7 @@ def update_kobodocker(dict_=None):
             dict_ = config.get_dict()
 
         # fetch new tags and prune
-        git_command = ['git', 'fetch', '-p']
+        git_command = ['git', 'fetch', '--prune', '--tags']
         CLI.run_command(git_command, cwd=dict_['kobodocker_path'])
 
         # checkout branch
@@ -101,7 +101,7 @@ def update_kobodocker(dict_=None):
     @staticmethod
     def update_koboinstall(version):
         # fetch new tags and prune
-        git_fetch_prune_command = ['git', 'fetch', '-p']
+        git_fetch_prune_command = ['git', 'fetch', '--prune', '--tags']
         CLI.run_command(git_fetch_prune_command)
 
         # checkout branch