Fix AWS Access

[ksemchh]

Description:
When connecting to public S3-buckets via boto3, an access error occurred:

botocore.exceptions.ClientError: An error occurred (AccessDenied) when calling the ListObjectsV2 operation: Access Denied

To solve this problem it was necessary to add the parameter signature_version=UNSIGNED when creating the S3 client, which disables request signing, allowing access to public buckets without AWS keys.

Сode changes:
In the S3 client initialization place (utils.py), Config and UNSIGNED are imported from botocore.

In the client constructor client(‘s3’, ...) the argument config=Config(signature_version=UNSIGNED) is passed.

PR checklist:

• Code is formatted (run scripts/format).
• Code lints properly (run scripts/lint).
• Tests pass (run scripts/test).
• Documentation has been updated to reflect changes, if applicable.
• Changes are added to the CHANGELOG.

[gadomski]

Can you use AWS_REQUEST_PAYER="requester" in your environment, instead?

[ksemchh]

Environment variable didn't work for me. The access error is still there.