chore(deps): bump actions/upload-artifact from 3 to 7

Bumps [actions/upload-artifact](https://github.com/actions/upload-artifact) from 3 to 7.
- [Release notes](https://github.com/actions/upload-artifact/releases)
- [Commits](https://github.com/actions/upload-artifact/compare/v3...v7)

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

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

.github/workflows/firmware-ci.yml

@@ -167,7 +167,7 @@ jobs:
           echo "See: https://github.com/espressif/qemu/wiki"
 
       - name: Upload firmware artifact (${{ matrix.variant }})
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v7
         with:
           name: esp32-csi-node-firmware-${{ matrix.variant }}
           path: firmware/esp32-csi-node/release-staging/