add metadata variable to unpacking

Because the metadata dict was added to MetadataQuery, we need to update the MetadataBaseFactory. A solution for the error below.

Error:

web_1       |   File "/data/geomagio/api/db/MetadataDatabaseFactory.py", line 34, in get_metadata

web_1       | ValueError: too many values to unpack (expected 12)

requested review from @erigler

assigned to @nshavers

approved this merge request

merged

mentioned in commit 7748845d