Downgrade golangci-lint action and version in CI

The CI workflow now uses golangci/golangci-lint-action@v6 with version v1.64.8 instead of v7 and v2.6.1, likely for compatibility or stability reasons.

Author: jferrl

.github/workflows/ci.yaml

@@ -14,9 +14,9 @@ jobs:
         with:
           go-version: "1.25.x"
       - name: golangci-lint
-        uses: golangci/golangci-lint-action@v7
+        uses: golangci/golangci-lint-action@v6
         with:
-          version: v2.6.1
+          version: v1.64.8
 
   test:
     runs-on: ubuntu-latest