Update workflows to actions/checkout@v6

Author: jwakely

.github/workflows/check-build.yml

@@ -18,7 +18,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v5
+    - uses: actions/checkout@v6
       with:
         fetch-depth: 1
 

.github/workflows/check-pr.yml

@@ -16,7 +16,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v5
+    - uses: actions/checkout@v6
       with:
         fetch-depth: 1
 

.github/workflows/deploy.yml

@@ -28,7 +28,7 @@ jobs:
 
     steps:
     - name: Clone XML sources
-      uses: actions/checkout@v5
+      uses: actions/checkout@v6
       with:
         ref: ${{ env.BRANCH }}
         # Using fetch-depth implies --single-branch so we don't fetch