Remove Sentry

Not used, and it has a quite a few outdated dependencies.

Dockerfile

@@ -22,14 +22,14 @@ FROM ${BUILDER_IMAGE} as builder
 
 # install build dependencies
 RUN apt-get update -y && apt-get install -y build-essential git \
-    && apt-get clean && rm -f /var/lib/apt/lists/*_*
+  && apt-get clean && rm -f /var/lib/apt/lists/*_*
 
 # prepare build dir
 WORKDIR /app
 
 # install hex + rebar
 RUN mix local.hex --force && \
-    mix local.rebar --force
+  mix local.rebar --force
 
 # set build ENV
 ENV MIX_ENV="prod"
@@ -61,7 +61,6 @@ RUN mix compile
 COPY config/runtime.exs config/
 
 COPY rel rel
-RUN mix sentry.package_source_code
 RUN mix release
 
 # start a new build stage so that the final image will only contain