Bump actions/download-artifact from 5 to 6 (#1599)

Author: Eirenliel

.github/workflows/gradle.yaml

@@ -158,7 +158,7 @@ jobs:
         with:
           submodules: recursive
 
-      - uses: actions/download-artifact@v5
+      - uses: actions/download-artifact@v6
         with:
           name: 'SlimeVR-Server'
           path: server/desktop/build/libs/
@@ -256,7 +256,7 @@ jobs:
         with:
           submodules: recursive
 
-      - uses: actions/download-artifact@v5
+      - uses: actions/download-artifact@v6
         with:
           name: 'SlimeVR-Server'
           path: server/desktop/build/libs/
@@ -336,7 +336,7 @@ jobs:
         with:
           submodules: recursive
 
-      - uses: actions/download-artifact@v5
+      - uses: actions/download-artifact@v6
         with:
           name: 'SlimeVR-Server'
           path: server/desktop/build/libs/