Update seerpy.py - Githubissues

Added functionality to return the date of when a report was uploaded to the Seer Cloud. I need this functionality to exclude older reports from analysis.

the new line is document['document.uploaded'] = document.pop('uploaded')

Note that the graphiql request in graphql.py already requests the uploaded date (in "GET_DOCUMENTS_FOR_STUDY_IDS_PAGED"). this request returns documents { id name uploaded fileSize downloadFileUrl }