fix: fix release workflow

Author: lanice

.github/workflows/release.yml

@@ -75,15 +75,4 @@ jobs:
           upload_url: ${{ steps.create_release.outputs.upload_url }}
           asset_path: ./manifest.json
           asset_name: manifest.json
-          asset_content_type: application/json
-
-      - name: Upload styles.css
-        id: upload-css
-        uses: actions/upload-release-asset@v1
-        env:
-          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
-        with:
-          upload_url: ${{ steps.create_release.outputs.upload_url }}
-          asset_path: ./styles.css
-          asset_name: styles.css
-          asset_content_type: text/css
+          asset_content_type: application/json