pkg/vm: fix GolangCI's SA4009 in RET()

SA4009: argument ctx is overwritten before first use (from staticcheck)

It should be OK here.

pkg/vm/vm_ops_flow.go

@@ -9,6 +9,7 @@ import (
 // RET Returns from the current context
 // Returns HALT if there are nomore context's to run
 func RET(op stack.Instruction, ctx *stack.Context, istack *stack.Invocation, rstack *stack.RandomAccess) (Vmstate, error) {
+	_ = ctx // fix SA4009 warning
 
 	// Pop current context from the Inovation stack
 	ctx, err := istack.PopCurrentContext()