[BUG] Broken BusyBox sed compatibility

[lens0021]

Describe the bug
Run cargo test while BusyBox sed falis

failures:

---- tests::stdlib::test_stdlib_src_tests_stdlib_capitalize_ab stdout ----
thread 'tests::stdlib::test_stdlib_src_tests_stdlib_capitalize_ab' panicked at src/tests/mod.rs:20:28:
assertion `left == right` failed
  left: "Uhello world"
error: test failed, to rerun pass `--bin amber`
 right: "Hello world"

---- tests::stdlib::test_stdlib_src_tests_stdlib_replace_regex_ext_ab stdout ----
thread 'tests::stdlib::test_stdlib_src_tests_stdlib_replace_regex_ext_ab' panicked at src/tests/mod.rs:20:28:
assertion `left == right` failed
  left: "abc123def\naeon aeons ### eons\n#path#to#file.txt"
 right: "abc[123]def\naeon aeons ### eons\n#path#to#file.txt"

---- tests::validity::test_validity_src_tests_validity_import_with_trailing_comma_ab stdout ----
thread 'tests::validity::test_validity_src_tests_validity_import_with_trailing_comma_ab' panicked at src/tests/mod.rs:20:28:
assertion `left == right` failed
  left: "bb\n3"
 right: "c\n3"


failures:
    tests::stdlib::test_stdlib_src_tests_stdlib_capitalize_ab
    tests::stdlib::test_stdlib_src_tests_stdlib_replace_regex_ext_ab
    tests::validity::test_validity_src_tests_validity_import_with_trailing_comma_ab

To Reproduce
A workflow is ready: #616
Or you can do that directly:

cargo run -- build src/tests/stdlib/capitalize.ab
cargo run -- build src/tests/stdlib/replace_regex_ext.ab
cargo run -- build src/tests/validity/import_with_trailing_comma.ab
docker run --rm -v $PWD:/root --workdir /root bash bash src/tests/stdlib/capitalize.sh
docker run --rm -v $PWD:/root --workdir /root bash bash src/tests/stdlib/replace_regex_ext.sh
docker run --rm -v $PWD:/root --workdir /root bash bash src/tests/validity/import_with_trailing_comma.sh

[lens0021]

The failure of tests::stdlib::test_stdlib_src_tests_stdlib_replace_regex_ext_ab is because of #619.

[lens0021]

import_with_trailing_comma.ab also includes replace_regex(), so the cause is the same as replace_regex_ext.ab