feat(gitlab): init

[Thomas-Philippot]

🎉 Theme for Gitlab 🎉

Gitlab is a online service to manage git repos with devops tools

💬 Additional Comments 💬

🗒 Checklist 🗒

• [x] I have read and followed Catppuccin's submission guidelines.
• [x] I have made a new directory underneath /styles/<name-of-website> containing the contents of the /template directory.
  • [x] I have ensured that the new directory is in lower-kebab-case.
  • [x] I have followed the template and kept the preprocessor as LESS.
• [x] I have made sure to update the userstyles.yml file with information about the new userstyle.
• [x] I have included the following files:
  • [x] catppuccin.user.css - all the CSS for the userstyle, based on the template.
  • [x] preview.webp - composite image of all four individual flavor screenshots (taken with the default accent color of mauve) stitched together, generated via Catwalk.