env_logger version bump broke the project

[djahandarie]

ffbc977 broke the project, because the actual rust code was not updated to match the changes across multiple env_logger major versions:

  Compiling hashpipe v0.2.0 (/build/source)
error[E0432]: unresolved import `env_logger::LogBuilder`
  --> src/main.rs:13:5
   |
13 | use env_logger::LogBuilder;
   |     ^^^^^^^^^^^^----------
   |     |           |
   |     |           help: a similar name exists in the module: `Builder`
   |     no `LogBuilder` in the root

For more information about this error, try `rustc --explain E0432`.
error: could not compile `hashpipe` due to previous error