fix: upgrade elliptic from 6.5.5 to 6.5.6

Snyk has created this PR to upgrade elliptic from 6.5.5 to 6.5.6.

See this package in npm:
elliptic

See this project in Snyk:
https://app.snyk.io/org/chai/project/930827c3-45bc-4efa-8fdf-714bd9cb0830?utm_source=github&utm_medium=referral&page=upgrade-pr

Author: snyk-bot

package-lock.json

@@ -32,7 +32,7 @@
     "assert": "^2.1.0",
     "bip39": "^3.1.0",
     "bn.js": "^5.2.1",
-    "elliptic": "~6.5.5",
+    "elliptic": "~6.5.6",
     "enc-utils": "^3.0.0",
     "ethereum-cryptography": "^2.2.0",
     "hash.js": "^1.1.7"