ci: add default_trait_access lint and fix its warnings

[cakebaker]

This PR adds the pedantic default_trait_access lint to the CICD and fixes its warnings.

[sylvestre]

I guess you saw the similar warnings:

error: use of `default` to create a unit struct
  --> src/uucore/src/lib/features/tokenize/num_format/formatters/floatf.rs:13:13
   |
13 |         Self::default()
   |             ^^^^^^^^^^^ help: remove this call to `default`
   |
   = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#default_constructed_unit_structs
   = note: `-D clippy::default-constructed-unit-structs` implied by `-D warnings`

error: use of `default` to create a unit struct
  --> src/uucore/src/lib/features/tokenize/num_format/formatters/scif.rs:13:13
   |
13 |         Self::default()
   |             ^^^^^^^^^^^ help: remove this call to `default`
   |
   = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#default_constructed_unit_structs

[cakebaker]

This is fixed in #5079