v3.9.0

• Add -c option to generate "Contributors" section like below. Here is the example of actionlint repository enabling the option. There are some notes on this option. Please read the document for more details. (#33, thanks @yottahmd)

  ## Contributors
  
  <a href="https://github.com/rhysd"><img src="https://wsrv.nl/?url=https%3A%2F%2Fgithub.com%2Frhysd.png&w=128&h=128&fit=cover&mask=circle" width="64" height="64" alt="@rhysd"></a>
  <a href="https://github.com/yottahmd"><img src="https://wsrv.nl/?url=https%3A%2F%2Fgithub.com%2Fyottahmd.png&w=128&h=128&fit=cover&mask=circle" width="64" height="64" alt="@yottahmd"></a>

• Fix crash when some external reference prefix contains a regex meta character.