Fix issues with Docker build problem

Had this problem:

$ docker build -t my-container-name .
[+] Building 0.3s (3/3) FINISHED
 => [internal] load build definition from Dockerfile                                   0.0s
 => => transferring dockerfile: 37B                                                    0.0s
 => [internal] load .dockerignore                                                      0.0s
 => => transferring context: 2B                                                        0.0s
 => ERROR [internal] load metadata for public.ecr.aws/lambda/python:3.8                0.1s
------
 > [internal] load metadata for public.ecr.aws/lambda/python:3.8:
------
failed to solve with frontend dockerfile.v0: failed to create LLB definition: unexpected status code [manifests 3.8]: 400 Bad Request

Based on this answer: https://stackoverflow.com/a/66993669/102401

I figured I'd troubleshoot with this:

DOCKER_BUILDKIT=0  docker build .

That command was successful and then I could run my original command and it worked. not sure what happened there, but that cleared whatever it was.