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/ci.yml

@@ -38,7 +38,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     steps:
       - name: Checkout
-        uses: actions/checkout@v2
+        uses: actions/checkout@v6
         with:
           clean: 'false'
           fetch-depth: '0'

.github/workflows/close-milestone.yml

@@ -8,7 +8,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v2.3.4
+        uses: actions/checkout@v6
         with:
           fetch-depth: 0
 

.github/workflows/dependabot-merge.yml

@@ -29,7 +29,7 @@ jobs:
         env:
           RUNNER_CONTEXT: ${{ toJson(runner) }}
         run: echo "$RUNNER_CONTEXT"
-      - uses: actions/checkout@v2.3.4
+      - uses: actions/checkout@v6
         with:
           ref: master
       - name: Dependabot Commenter

.github/workflows/draft-release.yml

@@ -10,7 +10,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v2.3.4
+        uses: actions/checkout@v6
         with:
           fetch-depth: 0
 

.github/workflows/sync-labels.yml

@@ -14,10 +14,10 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v2.3.4
+        uses: actions/checkout@v6
 
       - name: Checkout tools repo
-        uses: actions/checkout@v2.3.4
+        uses: actions/checkout@v6
         with:
           repository: RocketSurgeonsGuild/.github
           path: .rsg

.github/workflows/update-milestone.yml

@@ -12,7 +12,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v2.3.4
+        uses: actions/checkout@v6
 
       - name: sync milestones
         uses: RocketSurgeonsGuild/actions/sync-milestone@v0.2.4