Update to 22.04 in CI (#1485)

Author: helenye-stripe

.github/workflows/ci.yml

@@ -68,15 +68,14 @@ jobs:
           path: dist/
 
   test:
-    # Specific ubuntu version to support python 3.6 testing
-    # see https://github.com/actions/setup-python/issues/544#issuecomment-1332535877 for details
-    # move to ubuntu-latest when we drop 3.6
-    runs-on: ubuntu-20.04
+    # Specific ubuntu version to support python 3.7 testing
+    # see https://github.com/actions/setup-python/issues/544#issuecomment-1332535877 for list of supported versions
+    # move to ubuntu-latest when we drop 3.7
+    runs-on: ubuntu-22.04
     strategy:
       fail-fast: false
       matrix:
         python_version:
-          - "3.6"
           - "3.7"
           - "3.8"
           - "3.9"