Bump actions/checkout from 4 to 6

.github/workflows/documentation.yml

@@ -18,7 +18,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout current branch
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       # Copy additional markdown files to the Jekyll source directory
       - name: Copy CONTRIBUTING.md

.github/workflows/draft-pdf.yml

@@ -13,7 +13,7 @@ jobs:
     name: Paper Draft
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
       - name: Build draft PDF
         uses: openjournals/openjournals-draft-action@master
         with:

.github/workflows/macos-unit.yml

@@ -15,7 +15,7 @@ jobs:
     runs-on: macos-latest
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
 
       - name: Install libomp without linking
         run: |

.github/workflows/ubuntu-unit.yml

@@ -44,7 +44,7 @@ jobs:
             CXX: clang++-17
             compiler: clang-17 libomp-17-dev
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
 
       - name: update
         run: sudo apt update

.github/workflows/windows-unit.yml

@@ -16,7 +16,7 @@ jobs:
     runs-on: windows-latest
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
 
       - name: make build directory
         run: mkdir build_dir