fix: GitHub requires `.yml` extension (#6542)

* fix: GitHub requires `.yml` extension

Ref: https://docs.github.com/en/communities/using-templates-to-encourage-useful-issues-and-pull-requests/configuring-issue-templates-for-your-repository#configuring-the-template-chooser

* fix: remove newlines from multiline string

* fix: use textarea for dependencies list input