CI: upgrade to Python 3.10 (and PyPy 3.8)

Author: mgeier

.github/workflows/docs.yml

@@ -10,7 +10,7 @@ jobs:
       - name: Set up Python
         uses: actions/setup-python@v2
         with:
-          python-version: 3.9
+          python-version: "3.10"
       - name: Double-check Python version
         run: |
           python --version

.github/workflows/python-versions.yml

@@ -9,8 +9,10 @@ jobs:
           - "3.7"
           - "3.8"
           - "3.9"
+          - "3.10"
           - "pypy-3.6"
           - "pypy-3.7"
+          - "pypy-3.8"
     runs-on: ubuntu-latest
     steps:
       - name: Install PortAudio

.github/workflows/sounddevice-data.yml

@@ -16,7 +16,7 @@ jobs:
       - name: Set up Python
         uses: actions/setup-python@v2
         with:
-          python-version: 3.9
+          python-version: "3.10"
           architecture: ${{ matrix.arch }}
       - name: Double-check Python version
         run: |