master -> main in github workflows

[odockal]

Pull Request Checklist

General

• Is this a blocking issue or new feature? If yes, QE needs to +1 this PR

Code

• Are method-/class-/variable-names meaningful?
• Are methods concise, not too long?
• Are catch blocks catching precise Exceptions only (no catch all)?

Testing

• Are there unit-tests?
• Are there integration tests (or at least a jira to tackle these)?
• Is the non-happy path working, too?
• Are other parts that use the same component still working fine?

Function

• Does it work?

[odockal]

@sbouchet look please.