Merge branch 'fix/csp-mediaproxy-base-url' into 'develop'

HTTP security plug: add media proxy base url host to csp

See merge request !2638

lib/pleroma/plugs/http_security_plug.ex

@@ -113,6 +113,10 @@ defp get_proxy_and_attachment_sources do
         add_source(acc, host)
       end)
 
+    media_proxy_base_url =
+      if Config.get([:media_proxy, :base_url]),
+        do: URI.parse(Config.get([:media_proxy, :base_url])).host
+
     upload_base_url =
       if Config.get([Pleroma.Upload, :base_url]),
         do: URI.parse(Config.get([Pleroma.Upload, :base_url])).host
@@ -122,6 +126,7 @@ defp get_proxy_and_attachment_sources do
         do: URI.parse(Config.get([Pleroma.Uploaders.S3, :public_endpoint])).host
 
     []
+    |> add_source(media_proxy_base_url)
     |> add_source(upload_base_url)
     |> add_source(s3_endpoint)
     |> add_source(media_proxy_whitelist)