Use GraphQL v15 and v16 only

Author: kamilkisiela

.github/workflows/tests.yml

@@ -34,7 +34,6 @@ jobs:
     strategy:
       matrix:
         graphql_version:
-          - 14
           - 15
           - 16
     steps:
@@ -63,9 +62,8 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest] # remove windows to speed up the tests
-        node-version: [12, 14, 16, 18]
+        node-version: [12, 16, 18]
         graphql_version:
-          - 14
           - 15
           - 16
     steps: