libffi is no longer needed

Brent Cook · Brent Cook · commit d77e9acec055 · 2017-07-17T09:56:18.000-05:00
diff --git a/docker/Dockerfile b/docker/Dockerfile
@@ -24,7 +24,6 @@ RUN apk update && \
       bison \
       build-base \
       ruby-dev \
-      libffi-dev\
       openssl-dev \
       readline-dev \
       sqlite-dev \
