Run shellcheck as a github workflow

Author: hulthe

.github/workflows/shellcheck.yml

@@ -0,0 +1,22 @@
+on:
+  pull_request:
+  push:
+    branches:
+      - main
+
+name: "Trigger: Push action"
+permissions: {}
+
+jobs:
+  shellcheck:
+    name: Shellcheck
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - name: Run ShellCheck
+        uses: ludeeus/action-shellcheck@master
+        with:
+          ignore_names: >-
+            gradlew
+        env:
+          SHELLCHECK_OPTS: --external-sources