Fix Yaml import as Python no longer has it by default. (#535)

Also increase timeout for integration tests by 30 mins to 3h (usual completion time ~2:3x).

Author: tneymanov

cloudbuild_CI.yaml

@@ -56,4 +56,4 @@ steps:
       # - '--gs_dir bashir-variant_integration_test_runs'
 images:
   - 'gcr.io/${PROJECT_ID}/gcp-variant-transforms:${COMMIT_SHA}'
-timeout: 150m
+timeout: 180m

setup.py

@@ -44,7 +44,8 @@
     'mmh3<2.6',
     # Refer to issue #528
     'google-cloud-storage<1.23.0',
-    'pyfarmhash'
+    'pyfarmhash',
+    'pyyaml'
 ]
 
 REQUIRED_SETUP_PACKAGES = [