Remove GPG signing from version bump script

Author: pangpang20

tools/bump_version.py

@@ -166,7 +166,7 @@ def create_tag(self) -> None:
 
 {''.join(changes)}
 """
-        cmdline = ["git", "tag", "-a", "-s", "-m", msg, tag_name]
+        cmdline = ["git", "tag", "-a", "-m", msg, tag_name]
         sp.check_call(cmdline)
 
     def _parse_version_from_file(self, fp: Path) -> Version: