Fix typo PackageTest.yml

The CI wasn't correctly identifying the different python versions in the matrix.

.github/workflows/PackageTest.yml

@@ -21,7 +21,7 @@ jobs:
       - name: Install poetry
         run: |
           pip install poetry
-          poetry env use python${{ matrix.python_version }}
+          poetry env use python${{ matrix.python-version }}
 
       - name: Install dependencies
         run: poetry install --with tests