fix(manager/git-submodules): Fix branch detection for special branch value .

[AirOne70]

Fix branch detection due to GitSimple "--show-current" always returning empty values.

Changes

Use "--list" option instead of "--show-current" to get the name of the current branch.

Context

The current option was not working as expected, as it was always returning empty values :
{"all":[],"branches":{},"current":"","detached":false}
Due to this, the detected branch was always an empty string when using the special branch value .

Documentation (please check one with an [x])

• I have updated the documentation, or
• No documentation update is required

How I've tested my work (please select one)

I have verified these changes via:

• Code inspection only, or
• Newly added/modified unit tests, or
• No unit tests but ran on a real repository, or
• Both unit tests + ran on a real repository

[viceice]

please open an upstream issue. it should be fixed there too

[renovate-release]

🎉 This PR is included in version 37.100.1 🎉

The release is available on:

• GitHub release
• 37.100.1

Your semantic-release bot 📦🚀