Simplify the check with existing if

tools/run_tests/helper_scripts/build_python.sh

@@ -188,15 +188,11 @@ esac
 pip_install --upgrade setuptools==44.1.1
 pip_install --upgrade pip==19.3.1
 pip_install --upgrade cython
-if [ -z $($VENV_PYTHON -V | grep "Python 2.7") ]; then
+pip_install --upgrade six protobuf
-  pip_install --upgrade six enum34 protobuf
-else
-  pip_install --upgrade six protobuf
-fi
 
 if [ "$("$VENV_PYTHON" -c "import sys; print(sys.version_info[0])")" == "2" ]
 then
-  pip_install futures
+  pip_install --upgrade futures enum34
 fi
 
 pip_install_dir "$ROOT"