chore: bump version to "6.3.0" (#441)

* chore: bump version to `"6.3.0-RC.1"`

* chore: update package.json

Author: cowdan

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@cowprotocol/cow-sdk",
-  "version": "6.3.0-RC.0",
+  "version": "6.3.0",
   "license": "(MIT OR Apache-2.0)",
   "files": [
     "/dist"