Bump actions/checkout from 5 to 6

Bumps [actions/checkout](https://github.com/actions/checkout) from 5 to 6.
- [Release notes](https://github.com/actions/checkout/releases)
- [Commits](actions/checkout@v5...v6)

Author: DimitriPapadopoulos

.github/workflows/ci-i386.yml

@@ -16,7 +16,7 @@ jobs:
 
     steps:
       - name: Checkout source
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
         with:
           submodules: recursive
           fetch-depth: 0 # required for version resolution

.github/workflows/ci.yaml

@@ -22,7 +22,7 @@ jobs:
 
     steps:
       - name: Checkout source
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
         with:
           submodules: recursive
           fetch-depth: 0 # required for version resolution
@@ -88,7 +88,7 @@ jobs:
 
     steps:
       - name: Checkout source
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
         with:
           submodules: recursive
           fetch-depth: 0
@@ -142,7 +142,7 @@ jobs:
 
     steps:
       - name: Checkout source
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
         with:
           submodules: recursive
           fetch-depth: 0 # required for version resolution

.github/workflows/codeql-analysis.yml

@@ -32,7 +32,7 @@ jobs:
 
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       # Initializes the CodeQL tools for scanning.
       - name: Initialize CodeQL

.github/workflows/wheel.yaml

@@ -28,7 +28,7 @@ jobs:
       # note: cibuildwheel config-settings are set in pyproject.toml
 
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
         with:
           submodules: true
           fetch-depth: 0  # required for version resolution for nightly wheels
@@ -44,7 +44,7 @@ jobs:
     name: Build source distribution
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
         with:
           submodules: true
           fetch-depth: 0