testing php73 stack

* add new travis test
* remove temporarily few travis test to speed up the build
* --experimental args isn't required anymore

wo/cli/templates/wpcommon.mustache

@@ -25,7 +25,7 @@ location /wp-content/uploads {
         try_files $uri$webp_suffix $uri =404;
     }
     location ~ \.php$ {
-#Prevent Direct Access Of PHP Files From Web Browsers
+        #Prevent Direct Access Of PHP Files From Web Browsers
         deny all;
     }
 }