[fix] selfhst icons: icon list url invalid, set to active

- the previous CDN icon list url no longer works
- a list of all icons is mirrored to the JSDelivr CDN however
- there's no reason to set the engine to inactive now that we use public CDNs

searx/settings.yml

@@ -1869,7 +1869,6 @@ engines:
   - name: selfhst icons
     engine: selfhst
     shortcut: si
-    inactive: true
     disabled: true
 
   - name: sepiasearch