deps: Update ibokuri dependency url

[sea-grass]

Rewrites the protest dependency url in build.zig.zon (doesn't change the dependency version). Fixes the following error seen on latest Zig master (0.12.0-dev.2811+3cafb9655):

getty/build.zig.zon:13:20: error: unable to unpack git files: BadZlibHeader
            .url = "git+https://github.com/ibokuri/protest.git#bae398b701e763ef18480aa3cfcca103716996de",
                   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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To reproduce the error:

1. Add the latest Zig to your PATH
2. Clear Zig caches (to ensure Zig build will attempt to fetch the protest dependency instead of using a cached version; there might be a better way to do this that doesn't involve nuking the entire cache): rm -rf ~/.cache/zig; cd path/to/getty; rm -rf zig-cache zig-out
3. Run zig build
4. See the above error

[ibokuri]

Thanks for the patch!