Change Actions for pull_request_target

.github/workflows/build.yml

@@ -1,40 +1,15 @@
 name: build
 
 on:
-  push:
-  pull_request:
+  workflow_run:
+    workflows: ["check_style"]
+    types:
+      - completed
   schedule:
   - cron: '0 0 1 * *' # monthly
 
 jobs:
-
-  black:
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v1
-      - name: Set up Python
-        uses: actions/setup-python@v2
-        with:
-          python-version: '3.10'
-      - run: pip install black
-      - name: Check Style
-        run: black . --check
-      - name: Add comment to pull request if format is incorrect
-        if: failure()
-        uses: actions/github-script@v5
-        with:
-          github-token: ${{secrets.GITHUB_TOKEN}}
-          script: |
-            github.rest.issues.createComment({
-              issue_number: context.issue.number,
-              owner: context.repo.owner,
-              repo: context.repo.repo,
-              body: 'Please format your code with black version 21.12b0 before commiting changes. See the README for details'
-            })
-        
-
   build:
-    needs: black
     runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v2

check_style.yml

@@ -0,0 +1,32 @@
+name: check_style
+
+on:
+  push:
+  pull_request_target:
+
+jobs:
+
+  black:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v1
+      - name: Set up Python
+        uses: actions/setup-python@v2
+        with:
+          python-version: '3.10'
+      - run: pip install black
+      - name: Check Style
+        run: black . --check
+      - name: Add comment to pull request if format is incorrect
+        if: failure()
+        uses: actions/github-script@v5
+        with:
+          github-token: ${{secrets.GITHUB_TOKEN}}
+          script: |
+            github.rest.issues.createComment({
+              issue_number: context.issue.number,
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              body: 'Please format your code with black version 21.12b0 before commiting changes. See the README for details'
+            })
+