Make CI go on 8.1

Author: NattyNarwhal

.github/workflows/ci.yml

@@ -11,7 +11,7 @@ jobs:
   ubuntu:
     strategy:
       matrix:
-          version: ['7.3', '7.4', '8.0']
+          version: ['7.3', '7.4', '8.0', '8.1']
     runs-on: ubuntu-latest
     steps:
       - name: Checkout