[Awesome] GitLab executor icon should respect theme

[kieran-ryan]

Describe the bug

GitLab executor logo appears black in light and dark mode.

To Reproduce

1. Run npx allure awesome allure-results in a GitLab pipeline
2. Open the generated report and inspect the GitLab logo

Expected behavior

Icon either displays GitLab colours in both themes or otherwise adheres to a similar colour scheme as the GitHub equivalent.

Screenshots

The contrast is limited in dark mode and heavy in light mode.

The GitHub icon (see demo) is comparatively softer and respects the theme.

Desktop:

• OS: macOS
• Browser: Safari
• Allure: v3.0.0