Merge branch 'sz/update_dockerfile' into 'dev'

update dockerfile, set rust-slim to 1.70

See merge request !431

Dockerfile

 #### The image base should be the same as in .gitlab-ci.yml
 #### Second stage of the Dockerfile (below) should use the same base (rust:slim or it's parent)
-FROM rust:1.65-slim as cargo-build
+FROM rust:1.70-slim as cargo-build
 
 WORKDIR /usr/src/pod