Update actions/checkout action to v6

Author: renovate[bot]

.github/workflows/codeql-analysis.yml

@@ -42,7 +42,7 @@ jobs:
 
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       # Initializes the CodeQL tools for scanning.
       - name: Initialize CodeQL

.github/workflows/spm.yml

@@ -8,7 +8,7 @@ jobs:
   run:
     runs-on: macos-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: SwiftyLab/setup-swift@latest
       - name: Update Package.swift.json
         run: |

.github/workflows/test.yml

@@ -11,7 +11,7 @@ jobs:
   test:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Build
         run: |
           set -ex