Update arduino_test_runner.yml

Author: ripred

.github/workflows/arduino_test_runner.yml

@@ -18,6 +18,7 @@ jobs:
         run: |
           gem install arduino_ci
           echo "$(ruby -e 'print Gem.bindir')" >> $GITHUB_PATH
+          export PATH="$PATH:$(ruby -e 'print Gem.bindir')"
 
       - name: Verify arduino_ci installation
         run: arduino_ci --version