fix(app): add missing decap-cms-backend-gitea dependency

Author: fgnass

packages/decap-cms-app/package.json

@@ -35,6 +35,7 @@
     "decap-cms-backend-azure": "^3.1.3",
     "decap-cms-backend-bitbucket": "^3.1.4",
     "decap-cms-backend-git-gateway": "^3.2.2",
+    "decap-cms-backend-gitea": "^3.1.5",
     "decap-cms-backend-github": "^3.2.2",
     "decap-cms-backend-gitlab": "^3.2.2",
     "decap-cms-backend-proxy": "^3.1.4",