Use custom prebuilt ffmpeg

.dockerignore

@@ -1 +1,6 @@
-priv/static
+assets
+_build
+.cargo
+deps
+.elixir_ls
+priv

docker/app/Dockerfile

@@ -1,34 +1,12 @@
 FROM elixir:1.12.3-alpine
 
-RUN apk update \
-    && apk add inotify-tools build-base git npm nodejs file-dev libpng-dev gifsicle optipng libjpeg-turbo-utils librsvg imagemagick postgresql-client wget rust cargo \
-       x264-dev x265-dev libvpx-dev lame-dev opus-dev libvorbis-dev yasm \
+RUN (echo "https://github.com/philomena-dev/prebuilt-ffmpeg/raw/master"; cat /etc/apk/repositories) > /tmp/repositories \
+    && cp /tmp/repositories /etc/apk/repositories \
+    && apk update --allow-untrusted \
+    && apk add inotify-tools build-base git ffmpeg ffmpeg-dev npm nodejs file-dev libpng-dev gifsicle optipng libjpeg-turbo-utils librsvg imagemagick postgresql-client wget rust cargo --allow-untrusted \
     && mix local.hex --force \
     && mix local.rebar --force
 
-ADD https://api.github.com/repos/philomena-dev/FFmpeg/git/refs/heads/release/4.4 /tmp/FFmpeg_version.json
-RUN git clone --depth 1 https://github.com/philomena-dev/FFmpeg /tmp/FFmpeg \
-    && cd /tmp/FFmpeg \
-    && ./configure \
-      --prefix=/usr \
-      --enable-avresample \
-      --enable-avfilter \
-      --enable-gpl \
-      --enable-libmp3lame \
-      --enable-libvorbis \
-      --enable-libvpx \
-      --enable-libx264 \
-      --enable-libx265 \
-      --enable-postproc \
-      --enable-pic \
-      --enable-pthreads \
-      --enable-shared \
-      --disable-stripping \
-      --disable-static \
-      --disable-librtmp \
-      --enable-libopus \
-    && make -j$(nproc) install
-
 ADD https://api.github.com/repos/philomena-dev/cli_intensities/git/refs/heads/master /tmp/cli_intensities_version.json
 RUN git clone --depth 1 https://github.com/philomena-dev/cli_intensities /tmp/cli_intensities \
     && cd /tmp/cli_intensities \