Vessel

Commits
- b8ae943: Add `repr` to `Unit`. (Exahilosys)

Commits
- 3af0f63: Actually fix expose. (Exahilosys)

Commits
- 6255655: Remove importlib.metadata. (Exahilosys)
- e852ab2: Add readthedocs spec. (Exahilosys)
- 827df0c: Merge branch 'main' of https://github.com/Exahilosys/vessel (Exahilosys)
- 4d23c34: Add resolve, update and fix expose. (Exahilosys)

Additions

- Added `add` and `pop`.
- Added `copy` and `deepcopy` ability.

Changes

- `repr` is now used for inner values (instead of) `str`.

Fixes

- Allowed `cls` for `list` and `dict`.
- Fixed `list` updating with `flush`.

Additions

- Added `Field` `default` parameter.