chore: weekly lints for 2025-12-22 (#234)

As identified by [this
workflow](https://leanprover.zulipchat.com/#narrow/channel/513188-CSLib/topic/Weekly.20linting.20log/near/564936677).

---------

Co-authored-by: Fabrizio Montesi <famontesi@gmail.com>

Author: chenson2018

Cslib/Algorithms/Lean/MergeSort/MergeSort.lean

@@ -217,7 +217,6 @@ theorem mergeSort_time_le (xs : List α) :
     grw [merge_time]
     simp only [mergeSort_same_length]
     unfold timeMergeSortRec
-    grw [ih1,ih2]
     grind
 
 /-- Time complexity of mergeSort -/