Test using tf 2.2 for py 3.7 test

Author: sshane

.github/workflows/test.yml

@@ -14,7 +14,7 @@ jobs:
           - python-version: 3.6  # add custom tf-versions per python-version
             tf-version: 2.0.0b1
           - python-version: 3.7
-            tf-version: 2.1
+            tf-version: 2.2
     steps:
       - uses: actions/checkout@v2