chore: bump mypy from 1.19.1 to 1.20.0 (#463)

Bumps [mypy](https://github.com/python/mypy) from 1.19.1 to 1.20.0.
- [Changelog](https://github.com/python/mypy/blob/master/CHANGELOG.md)
- [Commits](python/mypy@v1.19.1...v1.20.0)

---
updated-dependencies:
- dependency-name: mypy
  dependency-version: 1.20.0
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

pyproject.toml

@@ -48,7 +48,7 @@ twyn = "twyn.cli:entry_point"
 [dependency-groups]
 dev = [
     "pytest>=7.1.3,<10.0.0",
-    "mypy>=0.982,<1.20",
+    "mypy>=0.982,<1.21",
     "pytest-cov<7,>=4",
     "ruff>=0.5.1,<0.15.9",
     "types-requests<3.0.0.0,>=2.32.4.20250611",