Composer cloud build (GoogleCloudPlatform#4607)

* add cloud build and requirements file

* pin requirements

* Update composer/workflows/requirements-composer.txt

Co-authored-by: Bu Sun Kim <[email protected]>

Co-authored-by: Bu Sun Kim <[email protected]>

Author: leahecole

composer/workflows/cloud-build.yaml

@@ -0,0 +1,5 @@
+# Job for keeping the test Python packages in the Test Cloud Composer Environment up to date
+steps:
+  - name: 'gcr.io/cloud-builders/gcloud'
+    args: ['composer', 'environments', 'update', 'composer-test', '--update-pypi-packages-from-file', 'requirements-composer.txt', '--location', 'us-central1']
+timeout: 3600s #set timeout to 1h. It's unusual for installing Python packages in a composer environment to take 1h to update. 

composer/workflows/requirements-composer.txt

@@ -0,0 +1,2 @@
+# requirements file for python packages installed in the composer environment, for more info, see https://cloud.google.com/composer/docs/how-to/using/installing-python-dependencies
+apache-airflow-backport-providers-google==2020.6.24

renovate.json

@@ -6,7 +6,7 @@
   "rebaseWhen": "never",
   "masterIssue": true,
   "pip_requirements": {
-    "fileMatch": ["requirements-test.txt"]
+    "fileMatch": ["requirements-test.txt", "requirements-composer.txt"]
   },
   "packageRules": [
     {