workaround pre-release not installing in test ci

Author: LucaMarconato

.github/workflows/test.yaml

@@ -49,7 +49,7 @@ jobs:
           pip install pytest-cov
       - name: Install dependencies
         run: |
-          pip install --pre -e ".[dev,test]"
+          pip install --pre -e ".[dev,test,pre]"
       - name: Test
         env:
           MPLBACKEND: agg