fix(emx2-pyclient): delete_records needs check on data input

[dtroelofsprins]

Is your feature request related to a problem? Please describe.
The records to be deleted using delete_records can either be in a file or in a list or dataFrame.
Even in the documentation it says:The records that are to be deleted are specified in either a CSV file, or in a list of primary key values, or a pandas DataFrame representing the table on the schema
This list however should be a list of dictionaries (example in the documentation also shows this).

When just a single list with PK's is entered, it even seems as if data has been deleted as the response is: INFO: Molgenis EMX2 Pyclient: Deleted data from MYSCHEMA::MYTABLE where in fact nothing has happened.

It would be good to include a check that it's actual a list of dictionaries and also make this more clear in the documentation.