Use go embed to load queries from static files (#607)

.github/workflows/checks.yml

@@ -11,9 +11,14 @@ jobs:
   tests:
     name: tests
     runs-on: ubuntu-latest
+    timeout-minutes: 30
+    strategy:
+      matrix:
+        pg_version: [12, 13, 14]
+
     services:
       postgres:
-        image: postgres:12
+        image: postgres:${{ matrix.pg_version }}
         env:
           POSTGRES_USER: postgres
           POSTGRES_PASSWORD: postgres