Typo fix, forbid unsafe code

[AlyoshaVasilieva]

error: useless lint attribute
 --> src\lib.rs:1:1
  |
1 | #[forbid(unsafe_code)]
  | ^^^^^^^^^^^^^^^^^^^^^^ help: if you just forgot a `!`, use: `#![forbid(unsafe_code)]`
  |
  = note: `#[deny(clippy::useless_attribute)]` on by default
  = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#useless_attribute

error: useless lint attribute
 --> src\client.rs:1:1
  |
1 | #[forbid(unsafe_code)]
  | ^^^^^^^^^^^^^^^^^^^^^^ help: if you just forgot a `!`, use: `#![forbid(unsafe_code)]`
  |
  = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#useless_attribute

#![forbid(unsafe_code)] in lib.rs is crate-level forbid of unsafe code