Remove docker steps from PR build process

.github/workflows/main_matrix.yml

@@ -150,12 +150,14 @@ jobs:
             release/device-*.bat
 
       - name: Docker login
+        if: ${{ github.event_name != 'pull_request_target' && github.event_name != 'pull_request' }}
         uses: docker/login-action@v2
         with:
           username: meshtastic
           password: ${{ secrets.DOCKER_TOKEN }}
 
       - name: Docker setup
+        if: ${{ github.event_name != 'pull_request_target' && github.event_name != 'pull_request' }}
         uses: docker/setup-buildx-action@v2
 
       - name: Docker build and push tagged versions
@@ -168,7 +170,7 @@ jobs:
           tags: meshtastic/device-simulator:${{ steps.version.outputs.version }}
 
       - name: Docker build and push
-        if: github.ref == 'refs/heads/master'
+        if: ${{ github.ref == 'refs/heads/master' && github.event_name != 'pull_request_target' && github.event_name != 'pull_request' }}
         uses: docker/build-push-action@v3
         with:
           context: .