[discourse-web] uglify-js 2 support has been dropped upstream

[Andrea Veri <averi src gnome org>]

commit e4c3e104ac5b7fc4bf09e44fc6f60ca882ddda61
Author: Andrea Veri <averi redhat com>
Date:   Fri Dec 6 15:57:52 2019 +0100

    uglify-js 2 support has been dropped upstream

 Dockerfile | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/Dockerfile b/Dockerfile
index d2dc57c..144449c 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -18,7 +18,7 @@ RUN apt update && \
     # Needed by init-assets.sh
     brotli && \
     # Fix https://meta.discourse.org/t/uglifier-error-during-assets-precompile/96970
-    npm install -g uglify-js@"<3" && \
+    npm install -g uglify-js && \
     # Install svgo
     npm install -g svgo && \
     # Install pngout