Bump elliptic from 6.5.1 to 6.5.3 in /packages/backend

Bumps [elliptic](https://github.com/indutny/elliptic) from 6.5.1 to 6.5.3.
- [Release notes](https://github.com/indutny/elliptic/releases)
- [Commits](indutny/elliptic@v6.5.1...v6.5.3)

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

packages/backend/package-lock.json

@@ -1230,9 +1230,9 @@ bluebird@^3.5.5:
   integrity sha512-XpNj6GDQzdfW+r2Wnn7xiSAd7TM3jzkxGXBGTtWKuSXv1xUV+azxAm8jdWZN06QTQk+2N2XB9jRDkvbmQmcRtg==
 
 bn.js@^4.0.0, bn.js@^4.1.0, bn.js@^4.1.1, bn.js@^4.4.0:
-  version "4.11.8"
-  resolved "https://registry.yarnpkg.com/bn.js/-/bn.js-4.11.8.tgz#2cde09eb5ee341f484746bb0309b3253b1b1442f"
-  integrity sha512-ItfYfPLkWHUjckQCk8xC+LwxgK8NYcXywGigJgSwOP8Y2iyWT4f2vsZnoOXTTbo+o5yXmIUJ4gn5538SO5S3gA==
+  version "4.11.9"
+  resolved "https://registry.yarnpkg.com/bn.js/-/bn.js-4.11.9.tgz#26d556829458f9d1e81fc48952493d0ba3507828"
+  integrity sha512-E6QoYqCKZfgatHTdHzs1RRKP7ip4vvm+EyRUeE2RF0NblwVvb0p6jSVeNTOFxPn26QXN2o6SMfNxKp6kU8zQaw==
 
 [email protected]:
   version "1.19.0"
@@ -2152,9 +2152,9 @@ [email protected]:
   integrity sha1-WQxhFWsK4vTwJVcyoViyZrxWsh0=
 
 elliptic@^6.0.0:
-  version "6.5.2"
-  resolved "https://registry.yarnpkg.com/elliptic/-/elliptic-6.5.2.tgz#05c5678d7173c049d8ca433552224a495d0e3762"
-  integrity sha512-f4x70okzZbIQl/NSRLkI/+tteV/9WqL98zx+SQ69KbXxmVrmjwsNUPn/gYJJ0sHvEak24cZgHIPegRePAtA/xw==
+  version "6.5.3"
+  resolved "https://registry.yarnpkg.com/elliptic/-/elliptic-6.5.3.tgz#cb59eb2efdaf73a0bd78ccd7015a62ad6e0f93d6"
+  integrity sha512-IMqzv5wNQf+E6aHeIqATs0tOLeOTwj1QKbRcS3jBbYkl5oLAserA8yJTT7/VyHUYG91PRmPyeQDObKLPpeS4dw==
   dependencies:
     bn.js "^4.4.0"
     brorand "^1.0.1"