[BUG] Wrong behavior when deleting asterisk in makdown files

[Bekaboo]

Let | be the cursor, in the following case pressing backspace will delete two asterisks in front of the cursor in markdown files, causing unbalanced italic markers:

**|** --> press backspace --> |**

Expected behavior: delete ** pair around curosr: *|*

Plugin config:

require('ultimate-autopair').setup({
  {
    '*',
    '*',
    ft = { 'markdown' },
    disable_start = true,
    disable_end = true,
  },
})