Update base dependency to include contracts-common directly

[Bargsteen]

Purpose

Update base dependency to include contracts common directly.

Changes

• Update base
• Update MSRV to 1.66

Checklist

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

[Bargsteen]

Had to update MSRV to 1.66, is that OK with you? @abizjak

[abizjak]

Had to update MSRV to 1.66, is that OK with you? @abizjak

Yes, it's fine. Just mention it in the Changelog.