Improve security by updating blst to version 0.3.12

[vtamara]

Is your feature request related to a problem? Please describe.
blst 0.3.11 produces segmentation faults in OpenBSD due to constants present in a text section instead of being in a read-only section. The problem was solved in version 0.3.12. See supranational/blst#206

Describe the solution you'd like
Update of blst

Describe alternatives you've considered

Additional context
Please see ava-labs/avalanchego#3079

[darioush]

Closing as the dependency is now updated