Feature request: Enable to change the deserializer body

[LucasCMFBraga]

Use case

I updated the schema of my application, changing the amount field from int to float to comply with my company's requirements. However, I noticed that the default JSON parser was losing floating-point precision during requests.

`
def test_api_gateway_resolver_numeric_value():
app = ApiGatewayResolver()

@app.post("/my/path")
def test_handler():
    return app.current_event.json_body

# WHEN calling the event handler
event = {}
event.update(LOAD_GW_EVENT)
event["body"] = '{"amount":  2.2999999999999998}'
event["httpMethod"] = "POST"

result = app(event, {})
# THEN process event correctly
assert result["statusCode"] == 200
assert result["multiValueHeaders"]["Content-Type"] == [content_types.APPLICATION_JSON]
assert result["body"] == '{"amount":  2.2999999999999998}' # assert '{"amount":2.3}' == '{"amount":  2.2999999999999998}'

`

Solution/User Experience

I've already implemented a solution and will be opening a PR soon.
The fix involves passing a custom deserializer instance to the ApiGatewayResolver constructor to handle floating-point precision correctly.

Alternative solutions

Acknowledgment

• This feature request meets Powertools for AWS Lambda (Python) Tenets
• Should this be considered in other Powertools for AWS Lambda languages? i.e. Java, TypeScript, and .NET

[boring-cyborg]

Thanks for opening your first issue here! We'll come back to you as soon as we can.
In the meantime, check out the #python channel on our Powertools for AWS Lambda Discord: Invite link