fix: add "slices" import back in

[michaelkedar]

#1329 removed the slices import in vulnerability_result.go, because it was no longer using it.
At the same time, #1385 added a new usage of the module.

Add the import back to make osv-scanner build again.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 69.02%. Comparing base (581d1a3) to head (a5db8f6).
Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1395      +/-   ##
==========================================
+ Coverage   68.76%   69.02%   +0.25%     
==========================================
  Files         184      185       +1     
  Lines       17719    17869     +150     
==========================================
+ Hits        12185    12334     +149     
- Misses       4875     4876       +1     
  Partials      659      659              

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[hogo6002]

Thanks Michael!