Add column data types to import_ids()

[justinrobinson1020]

Provides data types to the read_csv function in import_ids(). Previously, pandas parsed some numeric ids as floats adding trailing zeros that required removal. New data types are:

• birthdate is parsed as a datetime64
• age is parsed as a Float64
• draft_year, draft_round, draft_pick, draft_ovr, height, weight, and db_season are parsed as Int64
• all other fields including numeric ids are parsed as strings

[alecglen]

Good idea, thanks @justinrobinson1020! I'm going to merge this to the v1.0 release branch since it's technically a breaking change.