Bump actions/checkout from 2 to 6

Bumps [actions/checkout](https://github.com/actions/checkout) from 2 to 6.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v2...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] <support@github.com>

Author: dependabot[bot]

.github/workflows/build.yml

@@ -7,7 +7,7 @@ jobs:
     environment: ci
     runs-on: 'ubuntu-22.04'
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v6
       - uses: actions/setup-java@v2
         with:
           java-version: 8

.github/workflows/pullrequest.yml

@@ -9,7 +9,7 @@ jobs:
       matrix:
         java: [8,11,20]
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v6
       - uses: actions/setup-java@v2
         with:
           java-version: ${{ matrix.java }}
@@ -27,7 +27,7 @@ jobs:
       matrix:
         java: [8,11,20]
     steps:
-     - uses: actions/checkout@v2
+     - uses: actions/checkout@v6
      - uses: actions/setup-java@v2
        with:
            java-version: ${{ matrix.java }}
@@ -45,7 +45,7 @@ jobs:
       matrix:
         java: [8,11,20]
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v6
       - uses: actions/setup-java@v2
         with:
           java-version: ${{ matrix.java }}

.github/workflows/release.yml

@@ -9,7 +9,7 @@ jobs:
     environment: ci
     runs-on: 'ubuntu-22.04'
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v6
       - uses: actions/setup-java@v2
         with:
           java-version: 8