ci: use the actions from the specification's main branch

Author: ariesclark

.github/workflows/ci.yaml

@@ -39,9 +39,9 @@ jobs:
           repository: vrchatapi/vrchatapi-java
           ref: ${{ inputs.ref || github.ref }}
 
-      - uses: vrchatapi/specification/.github/actions/setup-generator@ci/modernise-actions
+      - uses: vrchatapi/specification/.github/actions/setup-generator@main
 
-      - uses: vrchatapi/specification/.github/actions/download@ci/modernise-actions
+      - uses: vrchatapi/specification/.github/actions/download@main
         with:
           bundle: openapi-legacy.yaml