ModernTaxonomyPicker - allowMultipleSelections = false, but panel allows multiple items to be selected

Version

Please specify what version of the library you are using: 3.18.1

If you are not using the latest release, please update and see if the issue is resolved before submitting an issue.

Expected / Desired Behavior / Question

When allowMultipleSelections is false, I shouldn't be able to select more than one item in the tree view.

Observed Behavior

Multiple items can be selected in the tree view in the panel. It still only allows selecting one item in the picker itself, but the treeview should not allow multiple selections.

Steps to Reproduce

<ModernTaxonomyPicker
                allowMultipleSelections={false}
                termSetId={this.state.businessGroupTermSetId}
                panelTitle="Select Business Group"
                label="Business Group or Unit"
                context={this.props.context}
              />

Then, just click the Label button to open the panel and try to select more than one.

A change in onPickerChange is most likely required to only select one item when allowMultipleSelections is false: https://github.com/pnp/sp-dev-fx-controls-react/blob/master/src/controls/modernTaxonomyPicker/taxonomyPanelContents/TaxonomyPanelContents.tsx#L66

pnp / sp-dev-fx-controls-react