ci: Include RuboCop filepaths check in syntax workflow

- The slowest part of the separate workflow was the repo checkout step,
  so include it in here to avoid the overhead.

.github/workflows/rubocop-filepaths.yml

@@ -1,29 +0,0 @@
-name: RuboCop filepaths
-
-on:
-  push:
-    branches:
-      - master
-  pull_request:
-
-jobs:
-  check:
-    runs-on: ubuntu-22.04
-    if: github.repository == 'Homebrew/brew'
-    steps:
-      - name: Checkout repo
-        uses: actions/checkout@v3
-
-      - name: Check public API docs
-        working-directory: Library/Homebrew
-        run: |
-          public_apis=$(git grep -l "@api public" | wc -l | tr -d ' ')
-          rubocop_docs=$(yq '.Style/Documentation.Include' .rubocop.yml | wc -l | tr -d ' ')
-
-          if [[ public_apis -ne rubocop_docs ]]
-          then
-            echo "All public Homebrew APIs should be included in the Style/Documentation RuboCop."
-            echo "There were ${public_apis} '@api public' lines but ${rubocop_docs} filepaths for the 'Style/Documentation' RuboCop."
-            echo "Add or remove the filepaths from Library/Homebrew/.rubocop.yml as appropriate."
-            exit 1
-          fi

.github/workflows/tests.yml

@@ -46,6 +46,19 @@ jobs:
 
       - run: brew typecheck
 
+      - name: Check RuboCop filepaths
+        working-directory: Library/Homebrew
+        run: |
+          public_apis=$(git grep -l "@api public" | wc -l | tr -d ' ')
+          rubocop_docs=$(yq '.Style/Documentation.Include' .rubocop.yml | wc -l | tr -d ' ')
+          if [[ public_apis -ne rubocop_docs ]]
+          then
+            echo "All public Homebrew APIs should be included in the Style/Documentation RuboCop."
+            echo "There were ${public_apis} '@api public' lines but ${rubocop_docs} filepaths for the 'Style/Documentation' RuboCop."
+            echo "Add or remove the filepaths from Library/Homebrew/.rubocop.yml as appropriate."
+            exit 1
+          fi
+
   tap-syntax:
     name: tap syntax
     needs: syntax