Bump actions/checkout from 4 to 6

.github/workflows/artifacts.yml

@@ -19,7 +19,7 @@ jobs:
       contents: write
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
         with:
           submodules: recursive
       - name: Set up Python

.github/workflows/pip-audit.yml

@@ -16,7 +16,7 @@ jobs:
 
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Install Python
         uses: actions/setup-python@v5

.github/workflows/publish_docs.yml

@@ -14,7 +14,7 @@ jobs:
       # NOTE: Needed to push to the repository.
       contents: write
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
         with:
           path: graphtage
       - name: Get the version
@@ -38,7 +38,7 @@ jobs:
           cd graphtage/docs
           make html
       - name: Checkout gh-pages branch
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
         with:
           ref: gh-pages
           path: gh-pages

.github/workflows/pythonpackage.yml

@@ -19,7 +19,7 @@ jobs:
         python-version: ["3.8", "3.9", "3.10", "3.11", "3.12", "3.13"]
 
     steps:
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@v6
     - name: Set up Python ${{ matrix.python-version }}
       uses: actions/setup-python@v5
       with:

.github/workflows/pythonpublish.yml

@@ -14,7 +14,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@v6
     - name: Set up Python
       uses: actions/setup-python@v5
       with: