Update deploy_book.yml

Author: firasm

.github/workflows/deploy_book.yml

@@ -25,10 +25,17 @@ jobs:
       uses: actions/setup-python@v2
       with:
         python-version: 3.8
+        
+    - name: cache installation
+      uses: actions/cache@v2
+      with:
+        path: ${{ env.pythonLocation }}
+        key: ${{ env.pythonLocation }}-${{ hashFiles('setup.py') }}-${{ hashFiles('requirements.txt') }}
 
     - name: Install dependencies
       run: |
         pip install -r requirements.txt
+        
     # Build the book
     - name: Build the book
       run: |