Update actions/checkout action to v6

Author: renovate[bot]

.github/workflows/ci.yaml

@@ -22,7 +22,7 @@ jobs:
     env:
       CC_TEST_REPORTER_ID: "${{ secrets.CC_TEST_REPORTER_ID }}"
     steps:
-    - uses: actions/checkout@v5
+    - uses: actions/checkout@v6
     - name: Set up Ruby
       uses: ruby/setup-ruby@v1
       with:

.github/workflows/openapi-generate.yml

@@ -11,7 +11,7 @@ jobs:
     env:
       INPUT_SPEC_VERSION: v4.0
     steps:
-    - uses: actions/checkout@v5
+    - uses: actions/checkout@v6
     - name: Set up system
       run: sudo apt install -y xq
     - name: OpenAPI Generate