The version of Python needs to be a string to separate 3.1 from 3.10.

.github/workflows/book.yml

@@ -33,7 +33,7 @@ jobs:
             - name: Set up Python 3.10
               uses: actions/setup-python@v4
               with:
-                python-version: 3.10
+                python-version: '3.10'
 
             # set up pygom
             - name: Build and install pygom