fix unhugging of tstring

Author: asottile

add_trailing_comma/_token_helpers.py

@@ -136,6 +136,10 @@ def fix_brace(
                 tokens[first_brace + 1].name == 'FSTRING_START' and
                 tokens[last_brace - 1].name == 'FSTRING_END'
             ) or
+            (
+                tokens[first_brace + 1].name == 'TSTRING_START' and
+                tokens[last_brace - 1].name == 'TSTRING_END'
+            ) or
             # don't unhug if it is a single line
             fix_data.remove_comma
     ):

tests/features/unhug_test.py

@@ -27,6 +27,10 @@
         'textwrap.dedent(f"""\n'
         '    hi\n'
         '""")',
+        # single triple-quoted tstring argument, don't unhug
+        'textwrap.dedent(t"""\n'
+        '    hi\n'
+        '""")',
     ),
 )
 def test_noop_unhugs(src):