Bump actions/checkout v4 and set dependabot to only bump its major versions (#101585)

* Bump actions/checkout from 2.0.0 to 4.1.4

Bumps [actions/checkout](https://github.com/actions/checkout) from 2.0.0 to 4.1.4.
- [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...v4.1.4)

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

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

* Set dependabot to bump github-actions to major versions; use checkout v4

* Ignore patch and minor updates to actions/checkout

---------

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Jeff Handley <jeffhandley@users.noreply.github.com>

.github/dependabot.yml

@@ -7,3 +7,6 @@ updates:
     open-pull-requests-limit: 5
     labels:
       - area-codeflow
+    ignore:
+      - dependency-name: "actions/checkout"
+        update-types: ["version-update:semver-patch","version-update:semver-minor"]

.github/workflows/aspnetcore-sync.yml

@@ -16,14 +16,14 @@ jobs:
     runs-on: windows-latest
     steps:
     - name: Checkout aspnetcore
-      uses: actions/checkout@v2.0.0
+      uses: actions/checkout@v4
       with:
         # Test this script using changes in a fork
         repository: 'dotnet/aspnetcore'
         path: aspnetcore
         ref: main
     - name: Checkout runtime
-      uses: actions/checkout@v2.0.0
+      uses: actions/checkout@v4
       with:
         # Test this script using changes in a fork
         repository: 'dotnet/runtime'

.github/workflows/bump-chrome-version.yml

@@ -16,7 +16,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - name: Setup Branch
         run: |
           git config user.name github-actions[bot]