Update GitHub action to only execute on main branch

.github/workflows/jupyter-book.yml

@@ -2,16 +2,17 @@ name: deploy-book
 
 # Run this when the master or main branch changes
 on:
-  push:
-    branches: [ main ]
-  pull_request:
-    branches: [ main ]
-    # If your git repository has the Jupyter Book within some-subfolder next to
-    # unrelated files, you can make this run only if a file within that specific
-    # folder has been modified.
-    #
-    # paths:
-    # - some-subfolder/**
+  branchs: [ main ]
+  # push:
+  #   branches: [ main ]
+  # pull_request:
+  #   branches: [ main ]
+  # If your git repository has the Jupyter Book within some-subfolder next to
+  # unrelated files, you can make this run only if a file within that specific
+  # folder has been modified.
+  #
+  # paths:
+  # - some-subfolder/**
 
 # This job installs dependencies, builds the book, and pushes it to `gh-pages`
 jobs: