Bump actions/download-artifact from 5 to 6

Bumps [actions/download-artifact](https://github.com/actions/download-artifact) from 5 to 6.
- [Release notes](https://github.com/actions/download-artifact/releases)
- [Commits](actions/download-artifact@v5...v6)

---
updated-dependencies:
- dependency-name: actions/download-artifact
  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-release.yml

@@ -58,7 +58,7 @@ jobs:
         uses: actions/setup-python@v5
 
       - name: Download WebUI artifacts 💾
-        uses: actions/download-artifact@v5
+        uses: actions/download-artifact@v6
         with:
           name: pixelit-webui
           path: pixelit-webui-artifact
@@ -95,7 +95,7 @@ jobs:
     if: startsWith(github.ref, 'refs/tags/')
     steps:
       - name: Download artifacts 💾
-        uses: actions/download-artifact@v5
+        uses: actions/download-artifact@v6
         with:
           name: pixelit-firmware
 
@@ -125,7 +125,7 @@ jobs:
           path: docs
 
       - name: Download artifacts 💾
-        uses: actions/download-artifact@v5
+        uses: actions/download-artifact@v6
         with:
           name: pixelit-firmware
           path: artifacts
@@ -164,7 +164,7 @@ jobs:
           repository: "pixelit-project/WebUI"
 
       - name: Download artifacts 💾
-        uses: actions/download-artifact@v5
+        uses: actions/download-artifact@v6
         with:
           name: pixelit-webui
           path: webui