modify pr-build workflow

Author: Sherry520

.github/workflows/pr-build.yml

@@ -10,15 +10,11 @@ jobs:
     steps:
     - uses: actions/checkout@v2
 
-    - name: Download bootstrap file
-      run: wget https://raw.githubusercontent.com/progit/progit2-pub/master/bootstrap.sh
-    - name: Run bootstrap
-      run: sh bootstrap.sh
     - name: Set up Ruby
       uses: ruby/setup-ruby@v1
       with:
         ruby-version: 2.7
         bundler-cache: true # runs 'bundle install' and caches installed gems automatically
 
     - name: Build book
-      run: bundle exec rake book:build_action
+      run: bundle exec rake book:build