write_records_to_tsv: Stop quoting output TSV

According to TSV specs,¹ there are no restrictions on special characters
other than tabs are not allowed in a field. This is different from the
CSV specs,² which require double quotes around fields that contain
special characters.

Since this function only produces TSVs, follow the TSV specs and stop
adding quotes.

Resolves <#1312>

¹ <https://www.iana.org/assignments/media-types/text/tab-separated-values>
² <https://datatracker.ietf.org/doc/html/rfc4180#page-2>

augur/io/metadata.py

@@ -483,7 +483,9 @@ def write_records_to_tsv(records, output_file):
             output_columns,
             extrasaction='ignore',
             delimiter='\t',
-            lineterminator='\n'
+            lineterminator='\n',
+            quoting=csv.QUOTE_NONE,
+            quotechar=None,
         )
         tsv_writer.writeheader()
         tsv_writer.writerow(first_record)

tests/io/test_metadata.py

@@ -466,7 +466,7 @@ def output_records():
 def expected_output_tsv():
     return (
         "strain\tcountry\tdate\n"
-        'SEQ_A\t"""USA"""\t2020-10-01\n'
+        'SEQ_A\t"USA"\t2020-10-01\n'
         "SEQ_T\tUSA\t2020-10-02\n"
     )