chore: remove bad grind _=_ annotation on List.contains_iff_mem

Author: kim-em

src/Init/Data/Array/Lemmas.lean

@@ -3761,7 +3761,7 @@ theorem contains_iff_exists_mem_beq [BEq α] {xs : Array α} {a : α} :
 -- With `LawfulBEq α`, it would be better to use `contains_iff_mem` directly.
 grind_pattern contains_iff_exists_mem_beq => xs.contains a
 
-@[grind _=_]
+@[grind =]
 theorem contains_iff_mem [BEq α] [LawfulBEq α] {xs : Array α} {a : α} :
     xs.contains a ↔ a ∈ xs := by
   simp

src/Init/Data/List/Lemmas.lean

@@ -2932,7 +2932,7 @@ theorem contains_iff_exists_mem_beq [BEq α] {l : List α} {a : α} :
 -- With `LawfulBEq α`, it would be better to use `contains_iff_mem` directly.
 grind_pattern contains_iff_exists_mem_beq => l.contains a
 
-@[grind _=_]
+@[grind =]
 theorem contains_iff_mem [BEq α] [LawfulBEq α] {l : List α} {a : α} :
     l.contains a ↔ a ∈ l := by
   simp

src/Init/Data/Vector/Lemmas.lean

@@ -2698,7 +2698,7 @@ theorem contains_iff_exists_mem_beq [BEq α] {xs : Vector α n} {a : α} :
 -- With `LawfulBEq α`, it would be better to use `contains_iff_mem` directly.
 grind_pattern contains_iff_exists_mem_beq => xs.contains a
 
-@[grind _=_]
+@[grind =]
 theorem contains_iff_mem [BEq α] [LawfulBEq α] {xs : Vector α n} {a : α} :
     xs.contains a ↔ a ∈ xs := by
   simp