Pin google-api-core (#1204)

http://b/264520478

Author: Philmod

Dockerfile.tmpl

@@ -359,6 +359,7 @@ RUN pip install --upgrade cython && \
     pip install category_encoders && \
     # google-cloud-automl 2.0.0 introduced incompatible API changes, need to pin to 1.0.1
     pip install google-cloud-automl==1.0.1 && \
+    pip install google-api-core==1.33.2 && \
     pip install google-cloud-bigquery==2.2.0 && \
     pip install google-cloud-storage && \
     pip install google-cloud-translate==3.* && \