[etherpad-web/oscp-backend] Restore font_family and font_size, install dependency npm missed

[Bartłomiej Piotrowski <bpiotrowski src gnome org>]

commit 0e5e38451fbc495e4532183bad192cbe4882869e
Author: Bartłomiej Piotrowski <bpiotrowski gnome org>
Date:   Wed May 13 09:10:15 2020 +0200

    Restore font_family and font_size, install dependency npm missed

 Dockerfile | 3 +++
 1 file changed, 3 insertions(+)
---
diff --git a/Dockerfile b/Dockerfile
index 7aa5c0c..0b21904 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -20,6 +20,9 @@ WORKDIR /opt/etherpad
 # Install a few default plugins:
 SHELL ["/usr/bin/scl", "enable", "rh-nodejs12"]
 RUN npm install ep_adminpads \
+    ep_etherpad-lite@>=1.5.1 \
+    ep_font_family \
+    ep_font_size \
     ep_headings2 \
     ep_font_color \
     ep_markdown \