build_and_activate_venv: virtualenv is not installed in macOS runner

Author: tomtseng

ci/build_and_activate_venv.sh

@@ -17,7 +17,7 @@ if [[ ${python_version} == "" ]]; then
   python_version="python3.8"
 fi
 
-virtualenv -p ${python_version} ${venv}
+${python_version} -m ${venv}
 # shellcheck disable=SC1090,SC1091
 source ${venv}/bin/activate