Add typing_extensions version to requirements

[mojoe12]

Hi team,

With an old typing_extensions version (4.5.0) I got this error when importing ismrmrd:

Traceback (most recent call last):
File "examples/demo.py", line 1, in
import ismrmrd
File "/home/jhutter/.local/lib/python3.8/site-packages/ismrmrd/init.py", line 7, in
from .file import File
File "/home/jhutter/.local/lib/python3.8/site-packages/ismrmrd/file.py", line 8, in
from .xsd import ToXML
File "/home/jhutter/.local/lib/python3.8/site-packages/ismrmrd/xsd/init.py", line 1, in
from .pyxb_compat import (CreateFromDocument, ToXML, ToDOM)
File "/home/jhutter/.local/lib/python3.8/site-packages/ismrmrd/xsd/pyxb_compat.py", line 3, in
from xsdata.formats.dataclass.parsers import XmlParser
File "/home/jhutter/.local/lib/python3.8/site-packages/xsdata/formats/dataclass/parsers/init.py", line 1, in
from xsdata.formats.dataclass.parsers.dict import DictDecoder
File "/home/jhutter/.local/lib/python3.8/site-packages/xsdata/formats/dataclass/parsers/dict.py", line 9, in
from xsdata.formats.dataclass.context import XmlContext
File "/home/jhutter/.local/lib/python3.8/site-packages/xsdata/formats/dataclass/context.py", line 7, in
from xsdata.formats.dataclass.models.builders import XmlMetaBuilder
File "/home/jhutter/.local/lib/python3.8/site-packages/xsdata/formats/dataclass/models/builders.py", line 23, in
from xsdata.formats.dataclass.typing import (
File "/home/jhutter/.local/lib/python3.8/site-packages/xsdata/formats/dataclass/typing.py", line 18, in
from typing_extensions import ForwardRef
ImportError: cannot import name 'ForwardRef' from 'typing_extensions' (/home/jhutter/.local/lib/python3.8/site-packages/typing_extensions.py)

It was fixed after upgrading typing_extensions to 4.12.0.