(core) Upgrade sortedcontainers, python_dateutil, and html5lib for better Python 3.10 compatibility

Summary:
Based on https://github.com/gristlabs/grist-core/pull/251. It may not look like it, but there's very little going on in this diff:

- Tweak the DATEVALUE doctest for Python 2/3 compatibility.
- Mirrors the PR's changes to requirements3.txt in requirements.txt, i.e. make the same dependency upgrades in Python 2.
- Make the same upgrades in the thirdparty folder for the Python 2 nacl sandbox.

Test Plan: Updated one doctest for dateutil. Checked changelog of sortedcontainers. html5lib is only used by messytables and isn't actually relevant.

Reviewers: paulfitz

Reviewed By: paulfitz

Differential Revision: https://phab.getgrist.com/D3609

sandbox/grist/functions/date.py

@@ -292,11 +292,16 @@ def DATEVALUE(date_string, tz=None):
   >>> DATEVALUE("asdf")
   Traceback (most recent call last):
   ...
-  dateutil.parser._parser.ParserError: Unknown string format: asdf
+  {}: Unknown string format: asdf
   """
   return dateutil.parser.parse(date_string).replace(tzinfo=_get_tzinfo(tz))
 
 
+DATEVALUE.__doc__ = DATEVALUE.__doc__.format(
+  "dateutil.parser._parser.ParserError" if six.PY3 else "ParserError"
+)
+
+
 def DAY(date):
   """
   Returns the day of a date, as an integer ranging from 1 to 31. Same as `date.day`.