test: move to cargo nextest

[reubeno]

Switches CI actions to use cargo nextest instead of cargo test. This required some changes to interactive tests that fail under nextest. A few tests were disabled to get this change in place; they'll need to be revisited subsequently.

Also shifted toward having the PR and CI tests use a recent, stable version of bash installed via Homebrew. That ensures consistency across the macOS and Linux tests, and somewhat insulates from any staleness of the system bash installed in the runner VM.

[github-actions[bot]]

Performance Benchmark Report

Benchmark name	Baseline (μs)	Test/PR (μs)	Delta (μs)	Delta %
expand_one_string	3.36 μs	3.36 μs	0.00 μs	⚪ Unchanged
instantiate_shell	59.78 μs	59.39 μs	-0.39 μs	⚪ Unchanged
instantiate_shell_with_init_scripts	24913.29 μs	25175.78 μs	262.49 μs	⚪ Unchanged
parse_bash_completion	5675.33 μs	5651.77 μs	-23.56 μs	⚪ Unchanged
parse_sample_script	9.04 μs	8.84 μs	-0.20 μs	🟢 -2.24%
run_echo_builtin_command	90.23 μs	91.11 μs	0.88 μs	⚪ Unchanged
run_one_builtin_command	111.03 μs	111.29 μs	0.26 μs	⚪ Unchanged
run_one_external_command	1854.36 μs	1866.65 μs	12.29 μs	⚪ Unchanged
run_one_external_command_directly	954.41 μs	962.68 μs	8.27 μs	⚪ Unchanged

Code Coverage Report: Only Changed Files listed

Package	Base Coverage	New Coverage	Difference
brush-core/src/commands.rs	🟢 91.48%	🟢 91%	🔴 -0.48%
brush-core/src/expansion.rs	🟢 95.29%	🟢 95.63%	🟢 0.34%
brush-core/src/namedoptions.rs	🟠 52.4%	🟠 52.88%	🟢 0.48%
brush-core/src/shell.rs	🟢 77.98%	🟢 77.68%	🔴 -0.3%
brush-shell/src/args.rs	🟠 66.67%	🟠 64.29%	🔴 -2.38%
brush-shell/src/main.rs	🟢 92.14%	🟢 91.43%	🔴 -0.71%
Overall Coverage	🟢 76.09%	🟢 76.09%	⚪ 0%

Minimum allowed coverage is 70%, this run produced 76.09%

[github-actions[bot]]

Test Results

  2 files    8 suites   47s :stopwatch: 424 tests 424 :white_check_mark: 0 :zzz: 0 :x: 848 runs  848 :white_check_mark: 0 :zzz: 0 :x:

Results for commit 1f8be606.

:recycle: This comment has been updated with latest results.