[Sphinx] [Automation] Make sure Issue -> PR conversion of code blocks is correct

[felix91gr]

As seen in #180 and #181, the conversion of code blocks introduces (or removes, depending on the POV) some indentation from the original, resulting in blocks that were of the form:

let bits : u32 = 61;
let shifts = vec![-1, 4, 40];
    
for sh in shifts {
    println!("{bits} << {sh} = {}", bits << sh);
}

Getting translated to sphinx like so:

let bits : u32 = 61;
  let shifts = vec![-1, 4, 40];
    
  for sh in shifts {
      println!("{bits} << {sh} = {}", bits << sh);
  }