Install twine for PyPI publishing

- Add twine installation to the build environment.
- This ensures twine is available for PyPI publishing.
- Move twine installation to after venv creation.

.gitea/workflows/ci.yml

@@ -55,7 +55,6 @@ jobs:
         run: |
           curl -LsSf https://astral.sh/uv/install.sh | sh
           echo "$HOME/.cargo/bin" >> $GITEA_PATH
-          uv pip install --system build twine
 
       - name: Publish to PyPI
         env:
@@ -63,6 +62,7 @@ jobs:
           TWINE_PASSWORD: ${{ secrets.PYPI_PASSWORD }}
         run: |
           uv venv .venv
+          uv pip install --system build twine
           source .venv/bin/activate
           uv run python -m build
           uv run python -m twine upload dist/*