fix(deps): update dependency ethers to v6

Author: renovate[bot]

package.json

@@ -49,7 +49,7 @@
     "@celo/identity": "^5.1.1",
     "@celo/utils": "^5.0.6",
     "@masa-finance/masa-sdk": "^4.7.4",
-    "ethers": "^5.8.0",
+    "ethers": "^6.15.0",
     "viem": "^2.8.16"
   },
   "files": [