Similarly to have we have with other commands, use Bash to speed it up.
Before:
```
$ hyperfine "brew list"
Benchmark 1: brew list
Time (mean ± σ): 559.9 ms ± 122.8 ms [User: 176.2 ms, System: 126.2 ms]
Range (min … max): 503.2 ms … 907.3 ms 10 runs
```
After:
```
$ hyperfine "brew list"
Benchmark 1: brew list
Time (mean ± σ): 223.7 ms ± 31.9 ms [User: 35.0 ms, System: 53.4 ms]
Range (min … max): 198.1 ms … 302.4 ms 10
```
Petty after comparison because someone on Homebrew/discussions compared
them:
```
$ hyperfine "brew list" "pip3 list"
Benchmark 1: brew list
Time (mean ± σ): 213.1 ms ± 22.8 ms [User: 34.2 ms, System: 49.2 ms]
Range (min … max): 191.2 ms … 272.3 ms 13 runs
Benchmark 2: pip3 list
Time (mean ± σ): 271.7 ms ± 4.6 ms [User: 191.9 ms, System: 40.0 ms]
Range (min … max): 264.7 ms … 281.4 ms 10 runs
Summary
brew list ran
1.28 ± 0.14 times faster than pip3 list
```
---
While we're here, also add the `HOMEBREW_CASKROOM` environment variable
to make things a bit cleaner and use `--caskroom` in documentation.
Co-authored-by: Carlo Cabrera <30379873+carlocab@users.noreply.github.com>
