Bump actions/checkout from 2 to 4

Bumps [actions/checkout](https://github.com/actions/checkout) from 2 to 4.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](https://github.com/actions/checkout/compare/v2...v4)

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

Signed-off-by: dependabot[bot] <support@github.com>
diff --git a/.github/workflows/mandatory_files.yml b/.github/workflows/mandatory_files.yml
index 9abf62f..ed95edc 100644
--- a/.github/workflows/mandatory_files.yml
+++ b/.github/workflows/mandatory_files.yml
@@ -31,7 +31,7 @@
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
         with:
           persist-credentials: false
 
diff --git a/.github/workflows/maven.yml b/.github/workflows/maven.yml
index abc1f29..f41f14e 100644
--- a/.github/workflows/maven.yml
+++ b/.github/workflows/maven.yml
@@ -29,7 +29,7 @@
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
         with:
           persist-credentials: false
 
diff --git a/.github/workflows/staging.yml b/.github/workflows/staging.yml
index 10fc2cb..16310cf 100644
--- a/.github/workflows/staging.yml
+++ b/.github/workflows/staging.yml
@@ -29,7 +29,7 @@
 
     steps:
       - name: 'Checkout main'
-        uses: actions/checkout@v2
+        uses: actions/checkout@v4
         with:
           path: 'src'
           persist-credentials: false
@@ -51,7 +51,7 @@
         working-directory: ./src
 
       - name: 'Checkout target'
-        uses: actions/checkout@v2
+        uses: actions/checkout@v4
         with:
           repository: 'apache/shiro-site'
           ref: 'asf-staging'