Add formatting action

.github/workflows/JuliaFormatter.yml

@@ -0,0 +1,51 @@
+name: Formatting Check
+
+on:
+  push:
+    branches:
+      - master
+    tags: '*'
+  pull_request:
+
+concurrency:
+  # Skip intermediate builds: always.
+  # Cancel intermediate builds: only if it is a pull request build.
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: ${{ startsWith(github.ref, 'refs/pull/') }}
+jobs:
+  format:
+    name: Julia ${{ matrix.version }} - ${{ matrix.os }} - ${{ matrix.arch }} - ${{ github.event_name }}
+    runs-on: ${{ matrix.os }}
+    strategy:
+      fail-fast: false
+      matrix:
+        version:
+          - '1'
+        os:
+          - ubuntu-latest
+        arch:
+          - x64
+    steps:
+      - uses: actions/[email protected]
+
+      - uses: dorny/[email protected]
+        id: filter
+        with:
+          filters: |
+            julia_file_change:
+              - added|modified: '**.jl'
+
+      - uses: julia-actions/setup-julia@latest
+        if: steps.filter.outputs.julia_file_change == 'true'
+        with:
+          version: ${{ matrix.version }}
+
+      - name: Apply JuliaFormatter
+        if: steps.filter.outputs.julia_file_change == 'true'
+        run: |
+          julia --color=yes .dev/herb_format.jl --verbose .
+
+      - name: Check formatting diff
+        if: steps.filter.outputs.julia_file_change == 'true'
+        run: |
+          git diff --color=always --exit-code