Missing config file check does not create PR when main branch becomes available

[ilveroluca]

I installed the LM app on a completely empty repository. The first check that runs is the "Missing config file" check. It noticed that the LM configuration file was missing. I suppose because there was no branch onto which to open a PR, it opened an issue with the text:

No lifemonitor.yaml configuration file found on this repository.
The lifemonitor.yaml should be placed on the root of this repository.

I later created a main branch, but the check did not open a PR with a configuration template.

Suggested fix.

• If reasonably feasible, the check should notice that the branch has been created after its first run and create a PR with the configuration template. It would also be nice if the check could add a comment to the original issue referencing the new PR, or alternatively if it could close the issue.
• If this is too hard, we should at least extend the text of the issue to provide a link to a template file for the configuration and maybe even to the documentation on how to complete it.

[kikkomep]

fixed in #378