OAuth library for nim allows insecure generation of state values by generateState - entropy too low and uses regular PRNG instead of CSPRNG

Vulnerability Description

In the OAuth library for nim prior to version 0.11, the `state` values generated by the `generateState` function do not have sufficient entropy. These can be successfully guessed by an attacker allowing them to perform a CSRF vs a user, associating the user's session with the attacker's protected resources. While `state` isn't exactly a cryptographic value, it should be generated in a cryptographically secure way. `generateState` should be using a CSPRNG. Version 0.11 modifies the `generateState` function to generate `state` values of at least 128 bits of entropy while using a CSPRNG.

References

• https://github.com/CORDEA/oauth/security/advisories/GHSA-332c-q46h-fg8f
• https://github.com/CORDEA/oauth/blob/b8c163b0d9cfad6d29ce8c1fb394e5f47182ee1c/src/oauth2.nim#L179