ENH: Automate clang-format of C++ source files

Author: Lee Newberg

.github/workflows/apply-clang-format.yml

@@ -0,0 +1,17 @@
+name: Apply clang-format to PR
+
+on:
+  pull_request:
+    types: [labeled]
+
+jobs:
+  clang-format:
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v2
+      with:
+         fetch-depth: 0
+    - uses: InsightSoftwareConsortium/ITKApplyClangFormatAction@master
+      with:
+        github-token: ${{ secrets.GITHUB_TOKEN }}

.github/workflows/clang-format-linter.yml

@@ -7,7 +7,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v1
+    - uses: actions/checkout@v2
     - uses: InsightSoftwareConsortium/ITKClangFormatLinterAction@master
       with:
         error-message: 'Code is inconsistent with ITK Coding Style. Add the *action:ApplyClangFormat* PR label to correct.'