fix: Remove unneeded apk packages from learn-ocaml-client image

Author: erikmd

Dockerfile

@@ -31,7 +31,7 @@ RUN opam install . --destdir /home/opam/install-prefix --locked
 FROM alpine:3.13 as client
 
 RUN apk update \
-  && apk add ncurses-libs libev gmp dumb-init msmtp git openssl \
+  && apk add ncurses-libs libev dumb-init openssl \
   && addgroup learn-ocaml \
   && adduser learn-ocaml -DG learn-ocaml