Describe the bug
The enum BorderType is used in the exported DottedBorderOptions but it is not exported so users who want to set the type must import the private src/enums.dart which gives an analyzer error.

To Reproduce
Try to ref the BorderType enum to pass it to DottedBorderOptions with only the following import:

import 'package:dotted_border/dotted_border.dart';

Expected behavior
It to work

Screenshots
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Additional context
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