Upgrade cardano-base dependency

[tdammers]

Description

Upgrade dependency on cardano-base in order to be compatible with upcoming versions of ouroboros-consensus.
In current versions of cardano-base, KES sign keys are stored in mlocked memory, and all operations involving them must now happen in IO or ST. In order to facilitate existing pure code that isn't security-critical (e.g., generating mock data for testing purposes), the previous pure KES API is now provided as UnsoundPureKES, which we use here.

Checklist

• Commit sequence broadly makes sense and commits have useful messages
• New tests are added if needed and existing tests are updated
• All visible changes are prepended to the latest section of a CHANGELOG.md for the affected packages.
  New section is never added with the code changes. (See RELEASING.md)
• When applicable, versions are updated in .cabal and CHANGELOG.md files according to the
  versioning process.
• The version bounds in .cabal files for all affected packages are updated.
  If you change the bounds in a cabal file, that package itself must have a version increase. (See RELEASING.md)
• Code is formatted with fourmolu (use scripts/fourmolize.sh)
• Cabal files are formatted (use scripts/cabal-format.sh)
• hie.yaml has been updated (use scripts/gen-hie.sh)
• Self-reviewed the diff

[lehins]

@tdammers Please get rid of any changes related to serialization.
I wish you would have asked me before you went on wasting a lot of time on introducing all those changes.

We need to get rid of all KES related serialization form ledger, since ledger codebase does not depend on KES at all. So, please revert all of the additions with respect to KES and get rid of any serialization functionality for KES that was provided before