ci: include CRL issuing distrib. point test gen in CI

This commit extends the existing `testgen.yml` workflow to also ensure
that running the CRL issuing distribution point testcase generation
produces no diffs from what's checked-in.

.github/workflows/testgen.yml

@@ -72,5 +72,9 @@ jobs:
         working-directory: ./tests/crl_distrib_point/
         run: python3 make_testcerts.py
 
+      - name: Generate CRL test files
+        working-directory: ./tests/crls/
+        run: python3 make_testcrls.py
+
       - name: Enforce no diff
         run: git diff --exit-code