Few update

[geronimo-iia]

Hello,

First thanks for our work and time, it was a very good start for us to use it.

In this PR, you could retrieve:

• Python 3 and dependencies:
  • Fix yam constructor DeprecationWarning and update PyYaml
  • Remove python 2, python 3.4 and 3.5 support, add 3.8, 3.9 test unit configuration
  • Update and separate dev dependencies from module dependencies
  • Align python syntax on version 3
• Integrate Change from Christophe Morio (https://github.com/lbncmorio/skew/tree/more-resources)
• Configuration:
  • Remove mandatory needs for skew.yaml (using iam metadata associated and default boto3 credentials initialization)
• aws client:
  • Fix Error and termination BUG with awsclient
  • Add boto3 config default with retries={"max_attempts": 20, "mode": "adaptive"}
• Resource Enumeration:
  • Fix resource enumeration when no resource type is define
  • Rewrote filtering resource and add a warning if filter operation is missing when needed
  • Fix bad component matchs operation if similar component share a common prefix (like elb and elbv2)
• Resource Loading
  • Change enumerate to avoir loading all resources loaded in memory
  • Add lazy loading of full data with method _load_extra_attribute on Resource
  • Add lazy load per item on Log group for log_streams, metric_filters, queries, subscriptions
• Additional Ressource and details:
  • Group users, policy inline and attached
  • kinesis description
  • S3 bucket properties (acl, encryption, logging, cors, policy, notifications, ...)
  • elbV2 and target group
  • Cloud front Domain
  • cloud search and region list update
  • opsworks availaible on 9 regions
  • api gateway
  • Name EC2 with Instane Id or Tag Name value if exists
  • Cloudtrail: fix enumeration and tags, add trail detail and trail status
  • Add json_dump with optional normalisation
  • Add ECR Registery
  • Add ECR Repository
  • Add Kms Key
  • Add service definition on ecs cluster
  • Add StepFunction (alias states)
  • Add Event rule
• Github:
  • update workflow
  • add a change log
  • update readme (example and command line)
• Add Command line utility

I heavy tested all of this resources against our aws account at work (a huge account...), before send it to you.
I known that's is difficult to review, but let me know.

Regards

Jerome