Add GitBench to GUI clients list

GitBench is a free, MIT-licensed, cross-platform desktop Git client
for working across many repositories at once.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: Zeejfps

data/guis/gitbench.yml

@@ -0,0 +1,12 @@
+---
+name: "GitBench"
+project_url: "https://gitbench.builtbyzee.com/"
+image_tag: "images/guis/gitbench@2x.png"
+platforms:
+  - "Windows"
+  - "Mac"
+  - "Linux"
+price: "Free"
+license: "MIT"
+order: 61
+---