Missing support for anonymous querying of public buckets

[iSWORD]

The AWS CLI has the option --no-sign-request to skip loading credentials so that one can query a public bucket anonymously.

S3p doesn't seem to support this option.

Example

sudo rm -f .aws/credentials
# this works
aws s3api list-objects-v2 --bucket sfuploads --region eu-west-1 --no-sign-request --no-paginate | head
# this throws a CredentialsProviderError
s3p ls --bucket sfuploads --region eu-west-1 --no-sign-request