dagster-dbt: get_metadata() should accept MutableMapping instead of Mapping

[sotte]

What's the issue?

I wanted to add some custom metadata fields to dbt assets. For this I created a custom DagsterDbtTranslator and implemented the get_metadata() method.
The method is defined like this:

    def get_metadata(self, dbt_resource_props: Mapping[str, Any]) -> Mapping[str, Any]:

SRC

Mapping implies that one should not change the mapping (and of course your linters tell you not to if you try "__setitem__" method not defined on type "Mapping[str, Any]").
Given that the docs say that one should add custom metadata fields this way, I would expect dbt_resource_props to be of type MutableMapping.

I suggest to either change the type annotation to MutableMapping or to make the docs clearer.

What did you expect to happen?

I expected either a MutableMapping or documentation that would be clearer.

How to reproduce?

Write your own translator like this:

class CustomDagsterDbtTranslator(DagsterDbtTranslator):
    def get_metadata(self, dbt_resource_props: Mapping[str, Any]) -> Mapping[str, Any]:
        metadata = super().get_metadata(dbt_resource_props)
        metadata["foo"] = "bar"
        return metadata

Dagster version

dagster, version 1.9.2

Deployment type

None

Deployment details

No response

Additional information

No response

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