Specify Python version for all jobs

Author: daneah

.github/workflows/ch07-packaging.yml

@@ -11,6 +11,8 @@ jobs:
       - uses: actions/checkout@v2
 
       - uses: actions/setup-python@v2
+        with:
+          python-version: "3.10"
 
       - name: Install tox
         run: python -m pip install tox
@@ -26,6 +28,8 @@ jobs:
       - uses: actions/checkout@v2
 
       - uses: actions/setup-python@v2
+        with:
+          python-version: "3.10"
 
       - name: Install tox
         run: python -m pip install tox
@@ -82,6 +86,8 @@ jobs:
       - uses: actions/checkout@v2
 
       - uses: actions/setup-python@v2
+        with:
+          python-version: "3.10"
 
       - name: Install build
         run: python -m pip install build
@@ -105,6 +111,8 @@ jobs:
       - uses: actions/checkout@v2
 
       - uses: actions/setup-python@v2
+        with:
+          python-version: "3.10"
 
       - name: Install cibuildwheel
         run: python -m pip install cibuildwheel==2.3.1