Goroutine in TimeoutWheel leaks

Test in Matrixcube failed because of goroutine leaks.

=== RUN   TestLogDBGetMaxIndexReturnsNoSavedLogErrorWhenMaxIndexIsNotSaved
    leak.go:138: Leaked goroutine: goroutine 141 [chan receive]:
        github.com/fagongzi/goetty/timewheel.(*TimeoutWheel).doTick(0xc0000c8080)
        	/matrixcube/vendor/github.com/fagongzi/goetty/timewheel/timewheel.go:291 +0x105
        created by github.com/fagongzi/goetty/timewheel.(*TimeoutWheel).Start
        	/matrixcube/vendor/github.com/fagongzi/goetty/timewheel/timewheel.go:227 +0x291
    leak.go:138: Leaked goroutine: goroutine 142 [chan receive]:
        github.com/fagongzi/goetty/timewheel.(*TimeoutWheel).doExpired(0xc0000c8080)
        	/matrixcube/vendor/github.com/fagongzi/goetty/timewheel/timewheel.go:379 +0x85
        created by github.com/fagongzi/goetty/timewheel.(*TimeoutWheel).Start
        	/matrixcube/vendor/github.com/fagongzi/goetty/timewheel/timewheel.go:228 +0x305
--- FAIL: TestLogDBGetMaxIndexReturnsNoSavedLogErrorWhenMaxIndexIsNotSaved (5.16s)