Use private browsing for Firefox

Author: mdmintz

seleniumbase/core/browser_launcher.py

@@ -96,6 +96,7 @@ def _create_firefox_profile(downloads_path, proxy_string):
     profile.set_preference("security.csp.enable", False)
     profile.set_preference(
         "browser.download.manager.showAlertOnComplete", False)
+    profile.set_preference("browser.privatebrowsing.autostart", True)
     profile.set_preference("browser.download.panel.shown", False)
     profile.set_preference(
         "browser.download.animateNotifications", False)