Updated rust to fix build and merged in dependabot PRs

With rust 1.41 the build was failing with errors such as:

According to the following pages this is due to a minimum requirement
of rust 1.42

rust-lang/rust#65721
diem/diem#3558

Updated to almost latest rust 1.51. 1.52 was released today but
is not available in the docker repository

Dockerfile

@@ -11,7 +11,7 @@ COPY tsconfig.json webpack.config.js /app/
 COPY src /app/src
 RUN npx webpack --mode production
 
-FROM rust:1.41 AS server-compiler
+FROM rust:1.51 AS server-compiler
 WORKDIR /app/server
 RUN mkdir /app/dist && touch --date "1 Jan 1970" /app/dist/index.html /app/dist/main.js
 COPY server /app/server