[BUG] change event giving isModified:false on any changes in signature component.

[SwamiVivekanandBG]

• Formio.js version: "~4.14.13"
• "@formio/angular": "~5.5.0-rc.10",
• Browser: ALL

Steps to Reproduce

In the signature component, when drawing on the signature pad or refreshing it, the (change) event emitter from
<formio (change)="onDataChange($event)">
is consistently emitting "isModified: false".
However, since the data is being modified, the expected behavior is for it to emit "isModified: true"

[lane-formio]

Is this the case with more recent versions?