Revert "Pin tox and uv versions, to fix CI (#335)"

Prefer to roll forward with newer versions of these tools. This library no longer supports Python 3.8, so the CI issue with newer tool versions no longer happens.

This reverts commit b7f5aae.

.github/workflows/ci.yml

@@ -39,7 +39,7 @@ jobs:
           check-latest: true
       - name: Install Python requirements
         run: |
-          pip install --upgrade 'tox==4.16.0' 'tox-uv==1.9.1' 'uv==0.2.21'
+          pip install --upgrade tox tox-uv
       - name: Test
         run: tox
         env: