S3Client breaking change: DEFAULT requests must pass operation_name

[graebm]

Issue: see: https://github.com/awslabs/aws-c-s3/pull/439

Description of changes:

• S3Client.make_request() now requires operation_name to be set when type is S3RequestType.DEFAULT. (see S3 API for canonical list of names)
• latest submodules:

  aws-c-cal          v0.6.15 -> v0.7.1
  aws-c-common       v0.9.21 -> v0.9.23
  aws-c-s3           v0.5.10 -> v0.6.0
  aws-lc             v1.29.0 -> v1.31.0
  s2n                v1.4.16 -> v1.4.17

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.