chore(deps): update actions/checkout action to v6

Author: renovate[bot]

.github/workflows/copilot-setup-steps.yml

@@ -15,7 +15,7 @@ jobs:
     permissions:
       contents: read
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: actions/setup-node@v5
         with:
           node-version: '22'

.github/workflows/main.yml

@@ -20,7 +20,7 @@ jobs:
         timeout-minutes: 60
         runs-on: ${{ matrix.os }}
         steps:
-            - uses: actions/checkout@v5
+            - uses: actions/checkout@v6
 
             - uses: actions/setup-node@v5
               with:
@@ -53,7 +53,7 @@ jobs:
         timeout-minutes: 60
         runs-on: ${{ matrix.os }}
         steps:
-            - uses: actions/checkout@v5
+            - uses: actions/checkout@v6
 
             - uses: actions/setup-node@v5
               with:
@@ -86,7 +86,7 @@ jobs:
         runs-on: ${{ matrix.os }}
 
         steps:
-            - uses: actions/checkout@v5
+            - uses: actions/checkout@v6
 
             - uses: actions/setup-node@v5
               with: