Remove redundant imports

[FreezyLemon]

These result in warnings on 1.78 (current nightly). For example:

warning: the item `Pixel` is imported redundantly
  --> src/bin/stats.rs:14:21
   |
10 | use av_metrics::video::*;
   |     -------------------- the item `Pixel` is already imported here
...
14 | use rav1e::{Packet, Pixel};
   |                     ^^^^^

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 88.54%. Comparing base (3c3a26f) to head (86e6045).
Report is 3 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3354      +/-   ##
==========================================
+ Coverage   88.52%   88.54%   +0.01%     
==========================================
  Files          89       89              
  Lines       28323    28355      +32     
==========================================
+ Hits        25074    25107      +33     
+ Misses       3249     3248       -1     

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[barrbrain]

Most of these are clearly redundant from the local context.