[Quantum] Do not display update message if version numbers are not available

src/quantum/azext_quantum/_version_check_helper.py

@@ -44,7 +44,7 @@ def check_version(config, reported_version, today):
         if latest_version_dict is not None:
             latest_version = latest_version_dict['version'].split(' ')[0]
 
-        if reported_version != latest_version:
+        if reported_version != latest_version and reported_version is not None and latest_version is not None:
             return (f"\nVersion {reported_version} of the quantum extension is installed locally,"
                     f" but version {latest_version} is now available.\n"
                     "You can use 'az extension update -n quantum' to upgrade.\n")

src/quantum/azext_quantum/tests/latest/test_quantum_workspace.py

@@ -104,11 +104,13 @@ def test_version_check(self):
         test_config = None
 
         message = check_version(test_config, test_current_reported_version, test_old_date)
-        assert test_current_reported_version in message
+        assert message is None
+        # Note: list_versions("quantum") fails during these tests, so latest version number cannot be determined.
+        # No message is generated if either version number is unavailable. 
 
         message = check_version(test_config, test_old_reported_version, test_old_date)
-        assert test_old_reported_version in message
+        assert message is None
 
         message = check_version(test_config, test_none_version, test_today)
-        assert message is None  # Note: list_versions("quantum") fails during these tests
+        assert message is None