Bump actions/checkout from 6 to 7

Bumps [actions/checkout](https://github.com/actions/checkout) from 6 to 7.
- [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/v6...v7)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-version: '7'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

.github/workflows/build-private.yml

@@ -22,7 +22,7 @@ jobs:
 
     steps:
       - name: "Check out code"
-        uses: actions/checkout@v6
+        uses: actions/checkout@v7
         with:
           fetch-depth: 0 # Required for WyriHaximus/github-action-get-previous-tag
 
@@ -73,7 +73,7 @@ jobs:
           node-version: '20.x'
 
       - name: "Checkout billing extension"
-        uses: actions/checkout@v6
+        uses: actions/checkout@v7
         with:
           repository: solidtime-io/extension-billing
           path: extensions/Billing
@@ -93,7 +93,7 @@ jobs:
         run: cd extensions/Billing && npm ci
 
       - name: "Checkout services extension"
-        uses: actions/checkout@v6
+        uses: actions/checkout@v7
         with:
           repository: solidtime-io/extension-services
           path: extensions/Services
@@ -111,7 +111,7 @@ jobs:
         run: cd extensions/Services && npm ci
 
       - name: "Checkout invoicing extension"
-        uses: actions/checkout@v6
+        uses: actions/checkout@v7
         with:
           repository: solidtime-io/extension-invoicing
           path: extensions/Invoicing