Mock spacewak gpg home directory

Mocked the SPACEWALK_GPG_HOMEDIR value to `~/gnupg/`, which is the
default directory for gpg, in order to execute the gpg tests outside
the uyuni-server

python/lzreposync/tests/test_lzreposync.py

@@ -7,6 +7,7 @@
 import shutil
 import time
 import unittest
+from unittest.mock import patch
 
 import pytest
 from psycopg2 import errors
@@ -1093,6 +1094,7 @@ def test_get_repositories_by_channel_label(self):
         self.assertEqual(repo_url, repo.source_url)
         self.assertEqual("N", repo.metadata_singed)
 
+    @patch('lzreposync.rpm_repo.SPACEWALK_GPG_HOMEDIR', '~/.gnupg/')
     def test_has_valid_gpg_signature(self):
         """
         NOTE!: to successfully run this test, you should have already added