title: Pin Rust version for a specific server
body: <p>I did a rust binary, which I compile in a ci with the rust docker image, tag rust:buster,
  as my server was ubuntu 18.04
  Lastly, I could not start the binary on the server anymore after the last compilation.
  The error was :</p>
  <p><code>/lib/x86_64-linux-gnu/libc.so.6: version `GLIBC_2.28' not found (required by /home/xxx/.bin/ctprods)</code></p>
  <p>Then I upgraded my server to ubuntu 21.10. The binary worked.</p>
  <p>I want to fix the rust version in the ci.</p>
  <p>Why did it stop working ?</p>
  <p>How do I find the rust version for my server ?</p>