feat: only install typing-extensions dependency when necessary

[nadobando]

Key information

• RFC PR: (leave this empty)
• Related issue(s), if known:
• Area: Parser
• Meet tenets: Yes

Summary

typing-extensions module is a backport for typing hint for old versions of python <= 3.5
in this project many times typing-extensions is imported to use the Literal type hint which is already natively included in python >= 3.8

Motivation

There is no need for this package in Python >= 3.8 and we are currently enforced to install it

Proposal

add if try/except blocks based on the python version

# aws_lambda_powertools/utilities/parser/types.py
import sys

if sys.version_info[0] >= 3 and sys.version_info[1] >= 8:
    from typing import Literal  # noqa: F401
else:
    try:
        from typing_extensions import Literal  # noqa: F401
    except ImportError:
        raise Exception("please install typing-extensions or upgrade to Python >= 3.8")

# aws_lambda_powertools/utilities/parser/models/dynamodb.py
from datetime import date
from typing import Any, Dict, List, Optional

from pydantic import BaseModel

from ..types import Literal


class DynamoDBStreamChangedRecordModel(BaseModel):
    ApproximateCreationDateTime: Optional[date]
    Keys: Dict[str, Dict[str, Any]]
    NewImage: Optional[Dict[str, Any]]
    OldImage: Optional[Dict[str, Any]]
    SequenceNumber: str
    SizeBytes: int
    StreamViewType: Literal["NEW_AND_OLD_IMAGES", "KEYS_ONLY", "NEW_IMAGE", "OLD_IMAGE"]

this is not really a design, it's more a check to wether import typing-extensions or not based on the system python version

in order to use it right instead of importing typing_extensions we can include the dependency in the file types.py and then import that dependency from the types.py as showed in the code blocks

Drawbacks

since this is not a design it's more an improvement of a dependency import I don't see a drawback

Rationale and alternatives

• What is the impact of not doing this?
  The impact of not doing this will be the used of a backport library which is not needed by the interpreter as it has the native implementation

Unresolved questions

no questions

[to-mc]

Thanks @nadobando! I'll have a look at the PR shortly.

[heitorlessa]

Now available in 1.10.2! Thank you very much for this