Add Dokeop provider (#813)

Co-authored-by: Vincent Piau <[email protected]>
Co-authored-by: Ben Ramsey <[email protected]>

Author: 3 people

docs/providers/thirdparty.md

@@ -43,6 +43,7 @@ Gateway | Composer Package | Maintainer
 [DigitalOcean](https://github.com/chrishemmings/oauth2-digitalocean) | chrishemmings/oauth2-digitalocean | [Chris Hemmings](https://github.com/chrishemmings)
 [Discord](https://github.com/wohali/oauth2-discord-new) | wohali/oauth2-discord-new | [Joan Touzet](https://github.com/wohali)
 [Docusign](https://github.com/AlaaSarhan/oauth2-docusign) | sarhan/oauth2-docusign | [Alaa Sarhan](https://github.com/AlaaSarhan)
+[Dokeop](https://github.com/dokeop/oauth2-dokeop) | dokeop/oauth2-dokeop | [Dokeop](https://github.com/dokeop)
 [Dribbble](https://github.com/crewlabs/oauth2-dribbble) | crewlabs/oauth2-dribbble | [Crew Labs](https://crew.co/labs)
 [Dropbox](https://github.com/stevenmaguire/oauth2-dropbox) | stevenmaguire/oauth2-dropbox | [Steven Maguire](https://github.com/stevenmaguire)
 [Drupal](https://github.com/chrishemmings/oauth2-drupal) | chrishemmings/oauth2-drupal | [Chris Hemmings](https://github.com/chrishemmings)