Bump checkout to v6 (#87)

.github/workflows/dependency-submission.yml

@@ -15,7 +15,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
         with:
           submodules: recursive
 

.github/workflows/dotnet-format.yml

@@ -14,7 +14,7 @@ jobs:
     runs-on: windows-latest
     steps:
 
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
         with:
           submodules: recursive
 

.github/workflows/dotnet.yml

@@ -15,7 +15,7 @@ jobs:
     steps:
 
     - name: Initialize and update submodules
-      uses: actions/checkout@v4
+      uses: actions/checkout@v6
       with:
         submodules: recursive
         

.github/workflows/publish.yml

@@ -11,7 +11,7 @@ jobs:
 
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Extract GitRef (version tag)
         run: echo "GIT_REF=${GITHUB_REF#refs/tags/}" >> $GITHUB_ENV