Support finally in continue on 3.8+

Thanks to [bpo-32489](https://bugs.python.org/issue32489) and sadly
for rejection of my [PEP 601](https://www.python.org/dev/peps/pep-0601/)
finally in continue is supported in 3.8+. I checked the blame and looks
like there was already a commit for the same subject, but that only
changes the test and not actually changes the checker (dfe7fba08e)

parso/python/errors.py

@@ -449,7 +449,11 @@ class _ContinueChecks(SyntaxRule):
                 in_loop = True
             if block.type == 'try_stmt':
                 last_block = block.children[-3]
-                if last_block == 'finally' and leaf.start_pos > last_block.start_pos:
+                if (
+                    last_block == "finally"
+                    and leaf.start_pos > last_block.start_pos
+                    and self._normalizer.version < (3, 8)
+                ):
                     self.add_issue(leaf, message=self.message_in_finally)
                     return False  # Error already added
         if not in_loop: