Chore(deps): Bump actions/checkout from 5 to 6

Bumps [actions/checkout](https://github.com/actions/checkout) from 5 to 6.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v5...v6)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

.github/workflows/pr-testing.yml

@@ -29,7 +29,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: checkout repo
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
         with:
           submodules: recursive
       - name: setup java
@@ -61,7 +61,7 @@ jobs:
         ruby: ['3.1', '3.2', '3.3', '3.4']
     steps:
       - name: checkout repo
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
         with:
           submodules: recursive
       - name: setup ruby
@@ -87,7 +87,7 @@ jobs:
     runs-on: ubuntu-24.04
     steps:
       - name: checkout repo
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
         with:
           submodules: recursive
       - name: setup ruby
@@ -110,7 +110,7 @@ jobs:
           distribution: temurin
           java-version: 17
       - name: checkout repo
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
       # newer versions cause lint errors
       # https://github.com/clj-kondo/clj-kondo/releases
       - name: Install clojure tools