Update confirm.go

[zen0bit]

Hopefully Fixes #488

First trying go don't beat me

Desired changes

Usage: gum confirm [<prompt>]

Ask a user to confirm an action

Arguments:
  [<prompt>]    Prompt to display.

Flags:
  -h, --help                 Show context-sensitive help.
  -v, --version              Print the version number

      --default              Default confirmation action
      --affirmative="Yes"    The title of the affirmative action
      --negative="No"        The title of the negative action
      --timeout=0            Timeout until confirm returns selected value or default if provided ($GUM_CONFIRM_TIMEOUT)

Style Flags
  --prompt.foreground=""           Foreground Color ($GUM_CONFIRM_PROMPT_FOREGROUND)
  --selected.foreground="230"      Foreground Color ($GUM_CONFIRM_SELECTED_FOREGROUND)
  --unselected.foreground="254"    Foreground Color ($GUM_CONFIRM_UNSELECTED_FOREGROUND)
  --selected.background="1"        Selected Background Color ($GUM_CONFIRM_SELECTED_BACKGROUND)
  --unselected.background="2"      Unselected Background Color ($GUM_CONFIRM_UNSELECTED_BACKGROUND)

[maaslalani]

Hey @zen0bit, thanks for the PR. I believe you would need to add these flags / options to confirm/options.go first and then use the values in confirm/command.go