Typping issue with Python 3.10 syntax

[Stéphane Brunner]

When I run:
```
from lxml import etree

a: etree.Element | None=None
```
I get:
```
TypeError: unsupported operand type(s) for |: '_cython_3_0_11.cython_function_or_method' and 'NoneType'
```

System information:
```
>>> print("%-20s: %s" % ('Python', sys.version_info))
Python : sys.version_info(major=3, minor=10, micro=14, releaselevel='final', serial=0)
>>> print("%-20s: %s" % ('lxml.etree', etree.LXML_VERSION))
lxml.etree : (5, 3, 0, 0)
>>> print("%-20s: %s" % ('libxml used', etree.LIBXML_VERSION))
libxml used : (2, 12, 9)
>>> print("%-20s: %s" % ('libxml compiled', etree.LIBXML_COMPILED_VERSION))
libxml compiled : (2, 12, 9)
>>> print("%-20s: %s" % ('libxslt used', etree.LIBXSLT_VERSION))
libxslt used : (1, 1, 42)
>>> print("%-20s: %s" % ('libxslt compiled', etree.LIBXSLT_COMPILED_VERSION))
libxslt compiled : (1, 1, 42)
```

[scoder (scoder)]

This is one of the things that https://github.com/lxml/lxml/pull/405 might solve.

[Stéphane Brunner (stephane-brunner)]

Hello,

Effectively, I confirm that is fixing my issue :-)

CU
Stéphane