increase csv limit in TSVDataSource (#477)

Summary:
Pull Request resolved: #477

My run faild with _csv.Error: field larger than field limit (131072) error before f107879186

Reviewed By: kartikayk

Differential Revision: D14845916

fbshipit-source-id: 9a059f9c1aa26b58c3f1dd666d94fae199558208

pytext/data/sources/tsv.py

@@ -2,6 +2,7 @@
 # Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved
 
 import csv
+import sys
 import threading
 from typing import Dict, List, Optional, Type
 
@@ -14,6 +15,7 @@ def __init__(self, file, field_names=None, delimiter="\t"):
         self.field_names = field_names
         self.delimiter = delimiter
         self._access_lock = threading.Lock()
+        csv.field_size_limit(sys.maxsize)
 
     def __iter__(self):
         can_acquire = self._access_lock.acquire(blocking=False)