x11/walker: update to 2.3.0

Changelog:

• https://github.com/abenz1267/walker/releases/tag/v2.0.0
• https://github.com/abenz1267/walker/releases/tag/v2.0.1
• https://github.com/abenz1267/walker/releases/tag/v2.0.2
• https://github.com/abenz1267/walker/releases/tag/v2.0.3
• https://github.com/abenz1267/walker/releases/tag/v2.0.4
• https://github.com/abenz1267/walker/releases/tag/v2.1.0
• https://github.com/abenz1267/walker/releases/tag/v2.1.1
• https://github.com/abenz1267/walker/releases/tag/v2.2.0
• https://github.com/abenz1267/walker/releases/tag/v2.2.1
• https://github.com/abenz1267/walker/releases/tag/v2.3.0

Reported by: GitHub (watch releases)