Bug: sigma collections errors are not merged

[c-dvl]

Hi,

SigmaCollection.errors is always empty because errors are not merged in the merge function.

Fix:

def merge(cls, collections : Iterable["SigmaCollection"], collect_errors) -> "SigmaCollection":
        """Merge multiple SigmaCollection objects into one and return it."""
        if collect_errors:
            return cls([
                rule
                for collection in collections
                for rule in collection
            ], [
                error
                for collection in collections
                for error in collection.errors
            ] )
        else:
            return cls([
            rule
            for collection in collections
            for rule in collection
        ])

In load_ruleset() function return cls.merge(sigma_collections, collect_errors)

Regards,
Céline