Git modified_files detect whole folder content changes

## What did you do?

ℹ Please replace this with what you did.
Dangerfile:
`git.modified_files.include?("some/folder/*")`

Run `danger local`

## What did you expect to happen?
Detect any changes in files inside certain folder, as the content of the folder is dynamic. Should there be any changes inside this folder, I want danger to detect and warn it

## What happened instead?
It seems current function only support for a certain file such as `build.gradle`. Is there a way to achieve a folder level changes detection?

## Your Environment

* Which CI are you running on? Bitrise
* Are you running the latest version of Danger? 7.0.1

Start by reproducing the reported `git.modified_files.include?("some/folder/*")` behavior with `danger local` on Danger 7.0.1, then trace the `git.modified_files` implementation and its matching behavior. Done means changes to any file inside a dynamically populated folder are detected and warned about, with coverage for the folder-level pattern.

Written by the indexing model from the issue text.