ENH: Update actions/checkout to version 4.

Author: hjmjohnson

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

@@ -9,7 +9,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v1
+    - uses: actions/checkout@v4
     - uses: InsightSoftwareConsortium/ITKApplyClangFormatAction@master
       with:
         github-token: ${{ secrets.GITHUB_TOKEN }}

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

@@ -7,5 +7,6 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v1
+    - uses: actions/checkout@v4
+
     - uses: InsightSoftwareConsortium/ITKClangFormatLinterAction@master