fix: install postgres client libs required to build pyscopg2 on M1 Macs

Note: this adds a lot of extra installation and possible bloat to the
image. Until psycopg2-binary is available for M1, maybe we could provide
a custom wheel.

See psycopg/psycopg2#1286 for details on
pyscopg2-binary availability for M1.

Dockerfile

@@ -3,7 +3,7 @@ FROM ubuntu:20.04
 WORKDIR /usr/src/app
 
 RUN apt-get update \
-    && apt-get install -y python3-pip
+    && apt-get install -y python3-pip libpq-dev
 
 COPY requirements /requirements