Remove setuptools version restriction

We're fine with current versions now.

.github/workflows/test.yml

@@ -24,7 +24,7 @@ jobs:
       - name: Install dependencies
         run: |
           python -m pip install --upgrade pip
-          python -m pip install 'setuptools>=18.5,<=39.0.0'
+          python -m pip install setuptools
           python -m pip install -r test-requirements.txt
       - name: Install old numpy
         run: |