Update release_version_cal.py

Author: AllyW

scripts/ci/release_version_cal.py

@@ -250,7 +250,8 @@ def extract_module_version_info(mod_update_info, mod):
     clean_mod_of_azdev(mod)
     print("Start generating base metadata")
     install_mod_of_last_version(pkg_name, pre_release)
-    gen_metadata_from_whl(pkg_name, cli_ext_path + base_meta_path)
+    base_meta_folder = os.path.join(cli_ext_path, base_meta_path)
+    gen_metadata_from_whl(pkg_name, base_meta_folder)
     remove_mod_of_last_version(pkg_name)
     print("End generating base metadata")
     base_meta_file = os.path.join(cli_ext_path, base_meta_path, "az_" + pkg_name + "_meta.json")