fix: disable Showcase Eval Check workflow until fixed

The check is failing on all PRs. Disable with `if: false` so it's
easy to re-enable once the eval webhook is working again.

Author: jpr5

.github/workflows/showcase_eval_check.yml

@@ -9,6 +9,7 @@ permissions:
 
 jobs:
   create-check:
+    if: false
     runs-on: ubuntu-latest
     timeout-minutes: 2
     permissions: