fix: string replacement with slashes

[reubeno]

Fixes the case where a string replacement contains / chars, e.g.:

${value/pattern/some/replacement}

[github-actions]

Test Results

  2 files    9 suites   1m 6s ⏱️
495 tests 495 ✅ 0 💤 0 ❌
979 runs  979 ✅ 0 💤 0 ❌

Results for commit 2f46ef9.

[github-actions]

Performance Benchmark Report

Benchmark name	Baseline (μs)	Test/PR (μs)	Delta (μs)	Delta %
expand_one_string	3.42 μs	3.42 μs	0.00 μs	⚪ Unchanged
instantiate_shell	60.30 μs	59.80 μs	-0.50 μs	⚪ Unchanged
instantiate_shell_with_init_scripts	31280.85 μs	30862.67 μs	-418.18 μs	⚪ Unchanged
parse_bash_completion	2756.24 μs	2731.44 μs	-24.80 μs	⚪ Unchanged
parse_sample_script	4.16 μs	4.22 μs	0.06 μs	🟠 +1.44%
run_echo_builtin_command	91.40 μs	90.88 μs	-0.52 μs	⚪ Unchanged
run_one_builtin_command	109.68 μs	108.92 μs	-0.76 μs	⚪ Unchanged
run_one_external_command	1938.94 μs	1982.11 μs	43.17 μs	🟠 +2.23%
run_one_external_command_directly	1008.83 μs	1036.82 μs	27.99 μs	⚪ Unchanged

Code Coverage Report: Only Changed Files listed

Package	Base Coverage	New Coverage	Difference
Overall Coverage	🟢 73.55%	🟢 73.55%	⚪ 0%

Minimum allowed coverage is 70%, this run produced 73.55%