chore(release): bump version to 2.2.0 (#5555)

## Summary

- Bumps `pyproject.toml` version from `2.0.0` → `2.2.0` to align with
the upcoming `v2.2.0` GitHub release tag.
- No code changes. Release notes will be published on the tag.

## Why now

`pyproject.toml` had drifted from the released tag (stayed at `2.0.0`
through `v2.1.0`). Aligning it ahead of `v2.2.0` so external tools that
read `pyproject.toml` see the same version as the GitHub release.

## Test plan

- [x] `uv run ruff check pyproject.toml` passes
- [ ] CI lint + tests pass on this PR

🤖 Generated with [Claude Code](https://claude.com/claude-code)

---------

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: MarkusNeusinger

pyproject.toml

@@ -1,7 +1,7 @@
 # pyproject.toml
 [project]
 name = "anyplot"
-version = "2.0.0"
+version = "2.2.0"
 description = "AI-powered plotting examples"
 authors = [{ name = "Markus Neusinger", email = "admin@anyplot.ai" }]
 requires-python = ">=3.13"