Trigger python container promote

Because Id68080575a30e4a08c99df0af603fbb65a0983bd didn't touch any of
the docker files (but just added new 3.9 builds) they didn't get
promoted.  Update timestamp to trigger this.

Change-Id: I6bf33936d4da773329900a2a52d09654087313d4

docker/python-base/Dockerfile

@@ -13,7 +13,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-# Comment to force rebuilds 2021-02-19 19:09UTC
+# Comment to force rebuilds Thu 06 May 2021 12:34:57 AEST
 
 ARG PYTHON_VERSION=3.7
 FROM docker.io/library/python:${PYTHON_VERSION}-slim

docker/python-builder/Dockerfile

@@ -13,7 +13,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-# Comment to force rebuilds 2021-02-19 19:09UTC
+# Comment to force rebuilds Thu 06 May 2021 12:35:27 AEST
 
 ARG PYTHON_VERSION=3.7
 FROM docker.io/library/python:${PYTHON_VERSION}-slim as fake-python