Request: Please support branches with emojis in their name

[jankeromnes]

Describe the bug

Trying to trigger Werft on a branch with an emoji in its name (e.g. refactor-🍌) fails with:

👎 cannot start job - please talk to whoever's in charge of your Werft installation

Example: gitpod-io/gitpod#3861 (comment)

To Reproduce
Steps to reproduce the behavior:

1. Create a branch with an emoji in its name (e.g. refactor-🍌)
2. Run Werft on it
3. It fails

Expected behavior
Werft should work & start a job.

Screenshots

Additional context
(none)