Update concordium-base dependency, rand and ed25519 dependencies

[orhoj]

Purpose

Concordium-base was updated (as we need some new functionality from wallet_library), and as concordium-base has updated some dependencies we also use, they had to be updated to be in sync.

Changes

• Updated dependency to concordium-base.
• Updated rand, ed25519-dalek and curve25519-dalek to the versions also used by concordium-base.

Checklist

• My code follows the style of this project.
• The code compiles without warnings.
• I have performed a self-review of the changes.
• I have documented my code, in particular the intent of the
  hard-to-understand areas.
• (If necessary) I have updated the CHANGELOG.