chore: Update README.md (#1806)

Author: ellie-ys

README.md

@@ -80,7 +80,7 @@ dependencies.
 ### Mac/Linux
 
 ```
-pip install virtualenv
+pip3 install virtualenv
 virtualenv <your-env>
 source <your-env>/bin/activate
 <your-env>/bin/pip install google-api-python-client