Use `brew --prefix` to get brew package config path for install script

We noticed the Bun package manager is excluding the install script for your package because it is slow. https://github.com/oven-sh/bun/blob/a305e99af5d9dbe74ffabfa5a3c0cfdf815ac71a/src/install/postinstall_optimizer.zig#L14-L19 In Deno we were looking into making a similar optimization, but we don't believe it would be good to override your preferences just so we can do better on an install benchmark. I was looking at the code and I believe that it should actually get the value from `brew --prefix` then `./lib/pkgconfig`. I'm not sure though. It is much faster to do this on my machine. ``` % hyperfine --warmup 5 "brew --prefix" "brew environment --plain" Benchmark 1: brew --prefix Time (mean ± σ): 22.9 ms ± 1.6 ms [User: 8.3 ms, System: 8.8 ms] Range (min … max): 18.8 ms … 29.1 ms 120 runs Benchmark 2: brew environment --plain Time (mean ± σ): 789.2 ms ± 65.3 ms [User: 209.1 ms, System: 139.0 ms] Range (min … max): 714.9 ms … 884.1 ms 10 runs Summary brew --prefix ran 34.41 ± 3.68 times faster than brew environment --plain ```