use poetry 1.5.1

Author: zyxue

.github/workflows/python-package.yml

@@ -24,8 +24,9 @@ jobs:
       with:
         python-version: ${{ matrix.python-version }}
     - name: Install dependencies
+      # poetry 1.5.1 is the last version that supports py37
       run: |
-        python -m pip install --upgrade pip poetry==1.8.4
+        python -m pip install --upgrade pip poetry==1.5.1
         poetry install
     - name: Lint
       run: |