Release 0.27.0 (#1330)

> [!IMPORTANT]
> Merging this pull request will create this release

## Breaking Changes

### Drop support for Python 3.9

Both `openapi-python-client` itself and any generated clients no longer
support Python 3.9.

### Generated models now use `from __future__ import annotations`

This simplifies using forward references with the newer union syntax.

## Features

### Upgrade generated clients to 3.10 union syntax

All generated types now use the `A | B` syntax instead of `Union[A, B]`
or `Optional[A]`.

## Fixes

- Drop generated `requires-python` upper bounds for uv and PDM (#1329)

### Change default Ruff hook to `--fix-only`

This should enable `openapi-python-client` to keep auto-fixing lints
(like removing unused imports) but _not_ fail to
generate when unfixable lints are violated.

Since it's now unlikely for breaking changes to affect our usage (and by
popular request), the upper bound of `ruff`
has been lifted. Newer versions of `openapi-python-client` should no
longer be required to support newer versions of `ruff`.

## Notes

- Minimum Typer version is now 0.16

Co-authored-by: knope-bot[bot] <152252888+knope-bot[bot]@users.noreply.github.com>

Author: knope-bot[bot]

.changeset/change_default_ruff_hook_to_fix_only.md

@@ -13,6 +13,40 @@ Programmatic usage of this project (e.g., importing it as a Python module) and t
 
 The 0.x prefix used in versions for this project is to indicate that breaking changes are expected frequently (several times a year). Breaking changes will increment the minor number, all other changes will increment the patch number. You can track the progress toward 1.0 [here](https://github.com/openapi-generators/openapi-python-client/projects/2).
 
+## 0.27.0 (2025-10-28)
+
+### Breaking Changes
+
+#### Drop support for Python 3.9
+
+Both `openapi-python-client` itself and any generated clients no longer support Python 3.9.
+
+#### Generated models now use `from __future__ import annotations`
+
+This simplifies using forward references with the newer union syntax.
+
+### Features
+
+#### Upgrade generated clients to 3.10 union syntax
+
+All generated types now use the `A | B` syntax instead of `Union[A, B]` or `Optional[A]`.
+
+### Fixes
+
+- Drop generated `requires-python` upper bounds for uv and PDM (#1329)
+
+#### Change default Ruff hook to `--fix-only`
+
+This should enable `openapi-python-client` to keep auto-fixing lints (like removing unused imports) but _not_ fail to 
+generate when unfixable lints are violated.
+
+Since it's now unlikely for breaking changes to affect our usage (and by popular request), the upper bound of `ruff` 
+has been lifted. Newer versions of `openapi-python-client` should no longer be required to support newer versions of `ruff`.
+
+### Notes
+
+- Minimum Typer version is now 0.16
+
 ## 0.26.2 (2025-10-06)
 
 ### Fixes

.changeset/drop_support_for_python_39.md

@@ -17,7 +17,7 @@ dependencies = [
     "ruff>=0.2",
 ]
 name = "openapi-python-client"
-version = "0.26.2"
+version = "0.27.0"
 description = "Generate modern Python clients from OpenAPI"
 keywords = [
     "OpenAPI",