Bump actions/checkout from 2.7.0 to 6.0.1

Bumps [actions/checkout](https://github.com/actions/checkout) from 2.7.0 to 6.0.1.
- [Release notes](https://github.com/actions/checkout/releases)
- [Commits](actions/checkout@v2.7.0...v6.0.1)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-version: 6.0.1
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

.github/workflows/ci.yml

@@ -17,7 +17,7 @@ jobs:
           '3.2',
         ]
     steps:
-    - uses: actions/checkout@ee0669bd1cc54295c223e0bb666b733df41de1c5 # v2.7.0
+    - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
     - uses: ruby/setup-ruby@dffc446db9ba5a0c4446edb5bca1c5c473a806c5 # v1.235.0
       with:
         ruby-version: ${{ matrix.ruby }}
@@ -27,7 +27,7 @@ jobs:
   valgrind:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@ee0669bd1cc54295c223e0bb666b733df41de1c5 # v2.7.0
+      - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
       - uses: ruby/setup-ruby@dffc446db9ba5a0c4446edb5bca1c5c473a806c5 # v1.235.0
         with:
           bundler-cache: true

.github/workflows/cibuildgem.yaml

@@ -17,7 +17,7 @@ jobs:
     runs-on: "${{ matrix.os }}"
     steps:
       - name: "Checkout code"
-        uses: "actions/checkout@v5"
+        uses: "actions/checkout@v6.0.1"
       - name: "Setup Ruby"
         uses: "ruby/setup-ruby@v1"
         with:
@@ -39,7 +39,7 @@ jobs:
     runs-on: "${{ matrix.os }}"
     steps:
       - name: "Checkout code"
-        uses: "actions/checkout@v5"
+        uses: "actions/checkout@v6.0.1"
       - name: "Setup Ruby"
         uses: "ruby/setup-ruby@v1"
         with: