Bump actions/checkout from 5 to 6

Bumps [actions/checkout](https://github.com/actions/checkout) from 5 to 6.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v5...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-and-publish-develop.yml

@@ -23,7 +23,7 @@ jobs:
       packages: write
     steps:
       - name: Checkout Repo
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - name: Set SHA
         id: sha

.github/workflows/build-and-publish-release.yml

@@ -61,12 +61,12 @@ jobs:
 
       # checkout opencost UI to allow access to actions
       - name: Checkout actions
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
         with:
           repository: 'opencost/opencost-ui'
 
       - name: Checkout Repo
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
         with:
           repository: 'opencost/opencost-ui'
           ref: '${{ steps.branch.outputs.BRANCH_NAME }}'

.github/workflows/build-test-image.yml

@@ -41,7 +41,7 @@ jobs:
       packages: write
     steps:
       - name: Checkout Repo
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
         with:
           ref: ${{ github.event.merge_group.head_sha || github.event.pull_request.head.sha }}
       - name: Set SHA

.github/workflows/build-test.yaml

@@ -13,7 +13,7 @@ jobs:
   frontend:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
         with:
           path: ./
 

.github/workflows/promote-to-demo.yaml

@@ -18,7 +18,7 @@ jobs:
       image_tag: ${{ steps.tags.outputs.IMAGE_TAG }}
     steps:
       - name: Checkout Repo
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
       - name: Set SHA
         id: sha
         run: |