fix(tag): disable gpgsign in test repos to prevent tag signing conflicts

Tag tests were failing due to global tag.gpgsign=true configuration forcing
all tags to be signed. Added explicit tag.gpgsign=false setting in test
repositories to ensure lightweight tags can be created without messages.

Author: eugener

Cargo.lock

@@ -606,6 +606,9 @@ mod tests {
             .set_user("Test User", "[email protected]")
             .unwrap();
 
+        // Disable tag signing for tests to ensure lightweight tags work
+        repo.config().set("tag.gpgsign", "false").unwrap();
+
         (repo, test_path)
     }