workflows: switch pre-commit job to ubuntu-slim

Save some resources.

Signed-off-by: Benjamin Gilbert <bgilbert@cs.cmu.edu>

Author: bgilbert

.github/workflows/validate.yml

@@ -12,7 +12,7 @@ permissions:
 jobs:
   pre-commit:
     name: Rerun pre-commit checks
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-slim
     steps:
       - name: Check out repo
         uses: actions/checkout@v5