Fix issue with MSSQL image not working on latest Ubuntu

Author: aidanharan

.github/workflows/ci.yml

@@ -11,7 +11,7 @@ on:
 jobs:
   test:
     name: Run test suite
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
 
     env:
       COMPOSE_FILE: docker-compose.ci.yml