chore: add prerelease-type for bridging package on next branch

Author: anxolin

.release-please-config.json

@@ -10,7 +10,8 @@
     },
     "packages/bridging": {
       "package-name": "@cowprotocol/sdk-bridging",
-      "release-type": "node"
+      "release-type": "node",
+      "prerelease-type": "rc"
     },
     "packages/common": {
       "package-name": "@cowprotocol/sdk-common",