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](actions/checkout@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>

.github/workflows/bicep.yml

@@ -26,7 +26,7 @@ jobs:
     continue-on-error: false
     steps: 
       - name: Checkout
-        uses: actions/checkout@v2
+        uses: actions/checkout@v4
       - name: bicep build
         id: bicep-build
         run: az bicep build -f mlz-ash.bicep

.github/workflows/super-linter.yml

@@ -20,7 +20,7 @@ jobs:
     name: lint-codebase
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
         with:          
           fetch-depth: 0 # Full git history is needed to get a proper list of changed files within `super-linter`
       - uses: github/super-linter/slim@v4 # use the slim linter since we don't use rust, dotenv, armttk, pwsh, or c#

.github/workflows/validate-bicep.yml

@@ -15,7 +15,7 @@ jobs:
     runs-on: ubuntu-latest
     continue-on-error: false
     steps: 
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
         with:
           ref: ${{ github.event.pull_request.head.sha }}
       - run: |

.github/workflows/validate-build-bicep.yml

@@ -18,7 +18,7 @@ jobs:
   validate-build:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
         with:
           ref: ${{ github.event.pull_request.head.sha }}
       - run: |