find: Fix -fstype with stacked mounts

[tavianator]

If you stack two mounts on top of each other, e.g.

# mount -t ext4 /dev/sdX /mnt
# mount -t f2fs /dev/sdY /mnt

then read_fs_list() will return two entries for that mount point. The
later one is the one with the correct type, since the later mount is on
top of the earlier one.

[codecov]

Codecov Report

Attention: Patch coverage is 50.00000% with 2 lines in your changes missing coverage. Please review.

Project coverage is 87.37%. Comparing base (b94b5f0) to head (cd87902).
Report is 13 commits behind head on main.

Files with missing lines	Patch %	Lines
src/find/matchers/printf.rs	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #532      +/-   ##
==========================================
- Coverage   87.38%   87.37%   -0.02%     
==========================================
  Files          31       31              
  Lines        6824     6826       +2     
  Branches      321      321              
==========================================
+ Hits         5963     5964       +1     
- Misses        630      631       +1     
  Partials      231      231              

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[Crypto-Darth]

Some minor clippy warnings here.

[tavianator]

@Crypto-Darth Thanks, fixed