[#1437] ir: Fix contextcheck linters

Signed-off-by: Dmitrii Stepanov <d.stepanov@yadro.com>

pkg/morph/event/handlers.go

@@ -1,11 +1,13 @@
 package event
 
 import (
+	"context"
+
 	"github.com/nspcc-dev/neo-go/pkg/core/block"
 )
 
 // Handler is an Event processing function.
-type Handler func(Event)
+type Handler func(context.Context, Event)
 
 // BlockHandler is a chain block processing function.
 type BlockHandler func(*block.Block)