Reapply "Test fewer versions"

This reverts commit 1d92eb1.

Author: decibel

.github/workflows/ci.yml

@@ -4,7 +4,7 @@ jobs:
   test:
     strategy:
       matrix:
-        pg: [17, 16, 15, 14, 13, 12, 11, 10, 9.6, 9.5, 9.4, 9.3, 9.2, 9.1, 9.0, 8.4, 8.3, 8.2]
+        pg: [17, 16, 15, 14, 13, 12, 11, 10]
     name: 🐘 PostgreSQL ${{ matrix.pg }}
     runs-on: ubuntu-latest
     container: pgxn/pgxn-tools