slog 2.8 deprecation warnings fix

[jendakol]

Hello, offering the upstream a tiny fix to get around some fresh deprecation warnings:

warning: use of deprecated macro `slog::slog_crit`: Use fully qualified macro slog::crit!(...) instead
  --> lib.rs:70:16
   |
70 | pub use slog::{slog_crit, slog_debug, slog_error, slog_info, slog_trace, slog_warn};
   |                ^^^^^^^^^
   |
   = note: `#[warn(deprecated)]` on by default

warning: use of deprecated macro `slog::slog_debug`: Use fully qualified macro slog::warn!(...) instead
  --> lib.rs:70:27
   |
70 | pub use slog::{slog_crit, slog_debug, slog_error, slog_info, slog_trace, slog_warn};
   |                           ^^^^^^^^^^

warning: use of deprecated macro `slog::slog_error`: Use fully qualified macro slog::crit!(...) instead
  --> lib.rs:70:39
   |
70 | pub use slog::{slog_crit, slog_debug, slog_error, slog_info, slog_trace, slog_warn};
   |                                       ^^^^^^^^^^

warning: use of deprecated macro `slog::slog_info`: Use fully qualified macro slog::info!(...) instead
  --> lib.rs:70:51
   |
70 | pub use slog::{slog_crit, slog_debug, slog_error, slog_info, slog_trace, slog_warn};
   |                                                   ^^^^^^^^^

warning: use of deprecated macro `slog::slog_trace`: Use fully qualified macro slog::trace!(...) instead
  --> lib.rs:70:62
   |
70 | pub use slog::{slog_crit, slog_debug, slog_error, slog_info, slog_trace, slog_warn};
   |                                                              ^^^^^^^^^^

warning: use of deprecated macro `slog::slog_warn`: Use fully qualified macro slog::warn!(...) instead
  --> lib.rs:70:74
   |
70 | pub use slog::{slog_crit, slog_debug, slog_error, slog_info, slog_trace, slog_warn};
   |                                                                          ^^^^^^^^^

• one even tinier clippy warning fix :)

[dpc]

Do we need to mark these names as deprecated too now?

[jendakol]

I took the least-effort path 😅 But it crossed my mind for a second, too. The decision is up to you 😉

[jendakol]

@dpc Bump pls :)