Add support for .bash test files

[Chemaclass]

📚 Description

Currently, only *test.sh files with sh extension are loaded as test files. We should support also .bash extension.

Idea from @akinomyoga, thanks!

🔖 Changes

• Extended file discovery now handles both “test.sh” and “test.bash” filenames, ensuring paths containing wildcards are correctly evaluated
• Documentation reflects that bashunit searches for “test.sh” or “test.bash” files and recommends using either extension with wildcards
• Help text clarifies that directories run all “test.sh” or “test.bash” files
• New snapshots verify that directories and wildcards include “bash_test.bash” during test execution

✅ To-do list

• I updated the CHANGELOG.md to reflect the new feature or fix
• I updated the documentation to reflect the changes