Clean up clippy lints

[github-actions[bot]]

LCOV of commit 45af7c2 during Rust workflow #348

Summary coverage rate:
  lines......: 85.8% (991 of 1155 lines)
  functions..: 49.3% (231 of 469 functions)
  branches...: no data found

Files changed coverage rate:
                     |Lines       |Functions  |Branches    
  Filename           |Rate     Num|Rate    Num|Rate     Num
  =========================================================
  src/config.rs      |96.2%    209|54.1%    98|    -      0
  src/zitadel.rs     |76.7%    317|31.7%   120|    -      0