Default architecture differs from AWS-CDK

[tl24]

The default architecture for the uv-python-lambda is ARM64 which differs from aws-lambda-python-alpha which is X86_64. Architecture differences between the host and the container can result in some very weird errors during the build such as:

ERROR: failed to solve: process "/bin/sh -c mkdir /tmp/pip-cache &&     chmod -R 777 /tmp/pip-cache &&     pip install uv==$UV_VERSION &&     rm -rf /tmp/pip-cache/*" did not complete successfully: exit code: 255

It also can lead to very slow build times if the host tries to emulate the architecture.