Fix pleroma build on new versions

Dockerfile

@@ -1,4 +1,4 @@
-FROM alpine:3.11
+FROM alpine:3.12
 
 ARG __VIA_SCRIPT
 RUN \
@@ -25,12 +25,11 @@ RUN \
         git curl rsync postgresql-client \
     && \
     apk add --no-cache --virtual .sdk \
-        build-base cmake \
+        build-base cmake file-dev \
     && \
     apk add --no-cache --virtual .runtime \
         imagemagick \
-        elixir erlang erlang-runtime-tools \
-        erlang-xmerl erlang-ssl erlang-ssh erlang-eldap erlang-mnesia
+        elixir erlang erlang-dev
 
 # Add entrypoint
 COPY ./entrypoint.sh /