[fix] Rename ccengine engine to openverse

The CC engine was merged with WordPress and renamed to Openverse

Source: https://wordpress.org/news/2021/05/welcome-to-openverse/

searx/engines/openverse.py

@@ -1,7 +1,7 @@
 # SPDX-License-Identifier: AGPL-3.0-or-later
 """
 
- Creative Commons search engine (Images)
+ Openverse (formerly known as: Creative Commons search engine) [Images]
 
 """
 

searx/settings.yml

@@ -363,10 +363,10 @@ engines:
       # for a German audience. It contains many English videos and many
       # German videos have English subtitles.
 
-  - name: ccengine
-    engine: ccengine
+  - name: openverse
+    engine: openverse
     categories: images
-    shortcut: cce
+    shortcut: opv
 
   # - name: core.ac.uk
   #   engine: core