Add support for pexels.com

[rDamascena]

Website: https://www.pexels.com/

Examples of URLs we normally use:

User profile: https://www.pexels.com/@nathan-moore-1300563/

Individual image: https://www.pexels.com/photo/sun-shining-between-the-trees-in-the-forest-onto-an-asphalt-road-17213600/

• Compressed: https://images.pexels.com/photos/17213600/pexels-photo-17213600.jpeg?cs=srgb&dl=pexels-jacint-bofill-17213600.jpg&fm=jpg

• Uncompressed: https://images.pexels.com/photos/17213600/pexels-photo-17213600.jpeg

Video: https://www.pexels.com/video/salt-shores-sea-salt-israel-16979063/

• Download: https://www.pexels.com/download/video/16979063/

Collections:

• https://www.pexels.com/collections/summer-solstice-j2zdph3/

• https://www.pexels.com/collections/time-lapse-videos-qmn4bhw/

[mikf]

Duplicate of #2286

[mikf]

• Compressed: https://images.pexels.com/photos/17213600/pexels-photo-17213600.jpeg?cs=srgb&dl=pexels-jacint-bofill-17213600.jpg&fm=jpg
• Uncompressed: https://images.pexels.com/photos/17213600/pexels-photo-17213600.jpeg

Both of these return the exact same file.

Anyway, the latest v1.28.4 release includes support for most of the listed URLs (91bd3e3)