[Bug] Dropdown multi select gets the previously selected state

[paigeflourin]

I created a component for my application that uses the Dropdown component of FluentUI. One thing i noticed is that when I am selecting values, it gets the previously selected item. I tried the "Controlled multi-select Dropdown" example in the documentation and it also behaves that way

FluentUI version: "@fluentui/react": "^8.72.1",

this is the onChange of my dropdown:

onChange = (event: React.FormEvent<HTMLDivElement>, item: IDropdownOption): void => {
    if (item) {

            console.log(item);
            console.log("prevState", this.state.selectedKeys);

            this.setState({
                selectedKeys: item.selected ? [...this.state.selectedKeys, item.key as string] : this.state.selectedKeys.filter(key => key !== item.key),
            }, () => this.props.setInputValue(this.state.selectedKeys))
        }
        console.log(this.state.selectedKeys);

    };

```
        <Dropdown
                label=""
                selectedKeys={this.props.selectedKeys}
                onChange={this.onChange.bind(this)}
                multiSelect={this.props.isMultiple}
                options={this.props.options}
                styles={dropdownStyles}
                required={this.props.isRequired}
                errorMessage={this.props.errorMessage}

            />