fix: time_t/Time warnings

[johanburati]

Fix the following warnings:

warning: type alias `time_t` is never used                                                                                                                    
  --> src/fs/fields.rs:35:10                                                                                                                                  
   |                                                                                                                                                          
35 | pub type time_t = i64;                                                                                                                                   
   |          ^^^^^^                                                                                                                                          
   |                                                                                                                                                          
note: the lint level is defined here                                                                                                                          
  --> src/main.rs:13:9                                                                                                                                        
   |                                                                           
13 | #![warn(unused)]                                                                                                                                         
   |         ^^^^^^                                                                                                                                           
   = note: `#[warn(dead_code)]` implied by `#[warn(unused)]`                                                                                                  
                                                                                                                                                              
warning: struct `Time` is never constructed                                    
   --> src/fs/fields.rs:211:12                                                 
    |                                                                                                                                                         
211 | pub struct Time {                                                                                                                                       
    |            ^^^^                                                                                                                                         
                                                                               
warning: `eza` (bin "eza") generated 2 warnings