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](https://github.com/actions/download-artifact/compare/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>

.github/workflows/build-libs.yml

@@ -94,23 +94,23 @@ jobs:
       - name: Clone Git repository
         uses: actions/checkout@v5
       - name: Retrieve dylib
-        uses: actions/download-artifact@v5
+        uses: actions/download-artifact@v6
         with:
           name: macos-dylib
       - name: Retrieve x64 DLL
-        uses: actions/download-artifact@v5
+        uses: actions/download-artifact@v6
         with:
           name: windows-x64-dll
       - name: Retrieve x64 DLL with ASIO support
-        uses: actions/download-artifact@v5
+        uses: actions/download-artifact@v6
         with:
           name: windows-x64-dll-asio
       - name: Retrieve Win32 DLL
-        uses: actions/download-artifact@v5
+        uses: actions/download-artifact@v6
         with:
           name: windows-Win32-dll
       - name: Retrieve Win32 DLL with ASIO support
-        uses: actions/download-artifact@v5
+        uses: actions/download-artifact@v6
         with:
           name: windows-Win32-dll-asio
       - name: Commit and push binaries (if there are changes)