Update to a recent docker image

that also has the modules installed we need

Author: coke

.github/workflows/test.yml

@@ -18,4 +18,4 @@ jobs:
       - name: Run tests
         run: ./util/github-action-test.sh t
         env:
-          TEST_IMAGE: docker.io/jjmerelo/perl6-doccer:latest
+          TEST_IMAGE: docker.io/coke/rakudo-docs-test