Update actions/checkout action to v6

Author: renovate[bot]

.github/workflows/publish.yml

@@ -9,7 +9,7 @@ jobs:
   npm:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: actions/setup-node@v6
         with:
           node-version: '24.x'
@@ -26,7 +26,7 @@ jobs:
         working-directory: gem
     steps:
       # Set up
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Set up Ruby
         uses: ruby/setup-ruby@v1
         with:

.github/workflows/test.yml

@@ -8,7 +8,7 @@ jobs:
   typescript:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: actions/setup-node@v6
         with:
           node-version: '24.x'
@@ -29,7 +29,7 @@ jobs:
         working-directory: gem
 
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Set up Ruby
         uses: ruby/setup-ruby@v1
         with: