fix: use correct Python version in release workflow (#67)

## Problem

The release workflow was using `${{ matrix.python-version }}` but
there's no matrix in this job. `setup-uv` fell back to the latest Python
(3.14), which caused `pydantic-core` to fail building from source — pyo3
0.24.1 only supports up to Python 3.13.

The `PYTHON_VERSION: "3.10"` env var was already defined but never
referenced.

## Fix

- `python-version: ${{ matrix.python-version }}` → `${{
env.PYTHON_VERSION }}`
- Remove `make install-dependencies` — not needed in the release job
(only `uv build` + publish)

## Next step

After merging, delete and re-create the `0.0.42` GitHub release to
re-trigger this workflow.

Author: micmarty-deepsense

.github/workflows/release.yml

@@ -17,14 +17,11 @@ jobs:
       - name: Install uv
         uses: astral-sh/setup-uv@v5
         with:
-          python-version: ${{ matrix.python-version }}
+          python-version: ${{ env.PYTHON_VERSION }}
 
       - name: Set up Python
         run: uv python install
 
-      - name: Install dependencies
-        run: make install-dependencies
-
       - name: Build artifact
         run: |
           uv build