ci don't run workflows twice on PRs

.github/workflows/arduino.yml

@@ -6,6 +6,7 @@ on:
     branches: [ master, release/v8.* ]
 jobs:
   lint:
+    if: ${{ github.event_name != 'pull_request' || github.repository != github.event.pull_request.head.repo.full_name }}
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v2

.github/workflows/build_micropython.yml

@@ -6,6 +6,7 @@ on:
 
 jobs:
   build:
+    if: ${{ github.event_name != 'pull_request' || github.repository != github.event.pull_request.head.repo.full_name }}
     name: Build ${{ matrix.port }} port
     runs-on: ubuntu-latest
     continue-on-error: true

.github/workflows/ccpp.yml

@@ -8,6 +8,7 @@ on:
 
 jobs:
   build:
+    if: ${{ github.event_name != 'pull_request' || github.repository != github.event.pull_request.head.repo.full_name }}
     runs-on: ubuntu-latest
     strategy:
       matrix:

.github/workflows/check_conf.yml

@@ -5,6 +5,7 @@ on:
 
 jobs:
   verify-conf-internal:
+    if: ${{ github.event_name != 'pull_request' || github.repository != github.event.pull_request.head.repo.full_name }}
     runs-on: ubuntu-latest
     steps:
       - name: Checkout

.github/workflows/check_style.yml

@@ -5,6 +5,7 @@ on:
 
 jobs:
   verify-formatting:
+    if: ${{ github.event_name != 'pull_request' || github.repository != github.event.pull_request.head.repo.full_name }}
     runs-on: ubuntu-latest
     steps:
       - name: Checkout