BLD/CI: Update package CI to test with conda/spin

Author: Kai-Striega

.github/workflows/pythonpackage.yml

@@ -1,4 +1,4 @@
-name: Python package
+name: Test package
 
 on: [push, pull_request]
 
@@ -12,14 +12,12 @@ jobs:
     steps:
     - uses: actions/checkout@v3
     - name: Set up Python ${{ matrix.python-version }}
-      uses: actions/setup-python@v4
+      uses: conda-incubator/setup-miniconda@v3
       with:
+        auto-update-conda: true
         python-version: ${{ matrix.python-version }}
-    - name: Install dependencies
-      run: |
-        python -m pip install --upgrade pip poetry
-        poetry env use ${{ matrix.python-version }}
-        poetry install --with=test
+        activate-environment: numpy-financial-dev
+        environment-file: environment.yml
     - name: Test with pytest
       run: |
-        poetry run pytest --doctest-modules
+        spin test -- --doctest-modules