Bump actions/download-artifact from 7 to 8

Bumps [actions/download-artifact](https://github.com/actions/download-artifact) from 7 to 8.
- [Release notes](https://github.com/actions/download-artifact/releases)
- [Commits](https://github.com/actions/download-artifact/compare/v7...v8)

---
updated-dependencies:
- dependency-name: actions/download-artifact
  dependency-version: '8'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

.github/workflows/ci_build_major_branch.yml

@@ -85,7 +85,7 @@ jobs:
           fetch-depth: 0
 
       - name: Download firmwares
-        uses: actions/download-artifact@v7
+        uses: actions/download-artifact@v8
         with:
           pattern: firmware-*
           path: .

.github/workflows/ci_build_major_branch_keymap.yml

@@ -88,7 +88,7 @@ jobs:
         run: pip3 install -r requirements-dev.txt
 
       - name: Get target definitions
-        uses: actions/download-artifact@v7
+        uses: actions/download-artifact@v8
         with:
           name: targets-${{ inputs.keymap }}
           path: .
@@ -140,7 +140,7 @@ jobs:
         uses: actions/checkout@v6
 
       - name: Download firmwares
-        uses: actions/download-artifact@v7
+        uses: actions/download-artifact@v8
         with:
           pattern: firmware-${{ inputs.keymap }}-*
           path: .