chore(Dockerfile): install pkg-config

docker/Dockerfile

@@ -9,16 +9,25 @@ run apt-get -y install git git-restore-mtime exiftool g++ npm libsodium-dev hask
 # TODO: review
 run apt-get -y install --no-install-recommends locales-all ca-certificates
 
+# frontend
 run npm install -g n
 run n 14.19.1
 
+# backend
 run stack install happy
 
 # run git restore-mtime
+# frontend-test
 run apt-get -y install chromium
 
+# frontend-test
 env CHROME_BIN=chromium
 
+# backend-dependencies
 run apt-get -y install libghc-zlib-dev
 
+# backend-dependencies
 run apt-get -y install libpq-dev
+
+# backend-dependencies
+run apt-get -y install pkg-config