use bash to utilize alias commands

Author: dashdanw

Diff for: cloudbuild.yaml

@@ -1,7 +1,7 @@
 steps:
   - id: api_python
     name: python:3.7
-    entrypoint: /bin/sh
+    entrypoint: /bin/bash
     args:
       - -c
       - "./run_tests.sh -p"