[Chore] morley-0.6.0

Description

Problem: we want to release morley more often and last release was more than a month ago. Moreover, soon we will move Lorentz outside of morley (TM-309) and it would be nice to make a release before that.

Solution: update version to 0.6.0, update changelog.

Related issue(s)

None

✅ Checklist for your Merge Request

Related changes (conditional)

• Tests (see short guidelines)

  • If I added new functionality, I added tests covering it.
  • If I fixed a bug, I added a regression test to prevent the bug from silently reappearing again.

• Documentation

  • I checked whether I should update the docs and did so if necessary:
    • README
    • Haddock
    • docs/
  • I updated the changelog if my changes are externally visible.

Stylistic guide (mandatory)

• My commits comply with the following policy.
• My code complies with the style guide.