Switch small CI workflows to ubuntu-slim runner

Author: zjwhitehead

.github/workflows/config.yml

@@ -11,7 +11,7 @@ concurrency:
 jobs:
   cpplint:
     name: CPP Lint
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-slim
     steps:
       - uses: actions/checkout@v6
         with:

.github/workflows/pr-labeler.yml

@@ -6,7 +6,7 @@ on:
 
 jobs:
   pr-labeler:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-slim
 
     steps:
       - uses: TimonVS/pr-labeler-action@v5