[Utilities] Re-enable allocation test from #2018

Author: odow

test/Utilities/functions.jl

@@ -1058,7 +1058,7 @@ function _test_canonicalization(
     @test MOI.Utilities.canonical(g) !== g
     # There are some changes to sorting in Julia v1.9 that now mean sorting
     # allocates.
-    # @test @allocated(MOI.Utilities.canonicalize!(f)) == 0
+    @test @allocated(MOI.Utilities.canonicalize!(f)) == 0
     return
 end