update nsfwCensorImage suggestion in config/description.exs

Turns out this is also used to set the default values in adminfe.
However, this URL may break with newer Akkoma-FE versions.
Instead, set this to blank so that it falls back to the default
NSFW cover image set at build time on Akkoma-FE.

config/description.exs

@@ -1184,7 +1184,7 @@
             logoMask: true,
             minimalScopesMode: false,
             noAttachmentLinks: false,
-            nsfwCensorImage: "/static/img/nsfw.74818f9.png",
+            nsfwCensorImage: "",
             postContentType: "text/plain",
             redirectRootLogin: "/main/friends",
             redirectRootNoLogin: "/main/all",
@@ -1285,7 +1285,7 @@
             type: {:string, :image},
             description:
               "URL of the image to use for hiding NSFW media attachments in the timeline",
-            suggestions: ["/static/img/nsfw.74818f9.png"]
+            suggestions: [""]
           },
           %{
             key: :postContentType,