Identify duplicate key in error message

[crabba]

It would be helpful to identify which key is duplicated, when reporting duplicate keys in e.g. run inputs

miniwdl/WDL/_parser.py

Line 511 in 8d9980a

raise Error.MultipleDefinitions(self._sp(meta), "duplicate keys in call inputs")

Current:

        d = dict()
        for k, v in items:
            if k in d:
                raise Error.MultipleDefinitions(self._sp(meta), "duplicate keys in call inputs")
            d[k] = v

Suggested:

                raise Error.MultipleDefinitions(self._sp(meta), f"duplicate key '{k}' in call inputs")