Parameter validation failed - "MemorySizeInMb", must be one of: MemorySizeInMB, MaxConcurrency, ProvisionedConcurrency

**Describe the bug**
getting an error when trying to create model endpoint config.

**To reproduce**

```
from sagemaker_core.resources import EndpointConfig, Endpoint
from sagemaker_core.main.shapes import ProductionVariant, ProductionVariantServerlessConfig

endpoint_config = EndpointConfig.create(
endpoint_config_name='endpoint-config',
production_variants=[
ProductionVariant(
variant_name='variantA',
model_name='MyModel',
serverless_config=ProductionVariantServerlessConfig(
memory_size_in_mb=1024,
max_concurrency=2
)
)
]
)
```

Getting error:
```
ParamValidationError: Parameter validation failed:
Missing required parameter in ProductionVariants[0].ServerlessConfig: "MemorySizeInMB"
Unknown parameter in ProductionVariants[0].ServerlessConfig: "MemorySizeInMb", must be one of: MemorySizeInMB,
MaxConcurrency, ProvisionedConcurrency
```

**Expected behavior**
No error raised.

**Screenshots or logs**
If applicable, add screenshots or logs to help explain your problem.

**Bug information**
A description of your system. Please provide:
- **SageMaker Core version**: 1.0.16
- **Python version**: 3.11

**Additional context**
I'm guessing that there's some case sensitive issue happening here...?

Start with ProductionVariantServerlessConfig and the EndpointConfig.create path shown in the reproduction. Trace how memory_size_in_mb is converted for ServerlessConfig, then rerun the example against SageMaker validation and confirm the endpoint configuration is created without the MemorySizeInMb/MemorySizeInMB error.

Written by the indexing model from the issue text.