Source S3: encoding validation fix, refactor and test

[roman-yermilov-gl]

What

A user gets a traceback in return If optional encoding field is not set. Instead of this we need to display a human readable error description

How

• Fix an error with incorrect data type passed to codecs.lookup. None type is replaced with empty string
• Fix error message. There was a problem with error_message varibale which is empty in cases when for loop validations is successfull
• Fix version dependency conflict
• Made small refactoring and unit test

[github-actions]

Before Merging a Connector Pull Request

Wow! What a great pull request you have here! 🎉

To merge this PR, ensure the following has been done/considered for each connector added or updated:

• PR name follows PR naming conventions
• Breaking changes are considered. If a Breaking Change is being introduced, ensure an Airbyte engineer has created a Breaking Change Plan.
• Connector version has been incremented in the Dockerfile and metadata.yaml according to our Semantic Versioning for Connectors guidelines
• You've updated the connector's metadata.yaml file any other relevant changes, including a breakingChanges entry for major version bumps. See metadata.yaml docs
• Secrets in the connector's spec are annotated with airbyte_secret
• All documentation files are up to date. (README.md, bootstrap.md, docs.md, etc...)
• Changelog updated in docs/integrations/<source or destination>/<name>.md with an entry for the new version. See changelog example
• Migration guide updated in docs/integrations/<source or destination>/<name>-migrations.md with an entry for the new version, if the version is a breaking change. See migration guide example
• If set, you've ensured the icon is present in the platform-internal repo. (Docs)

If the checklist is complete, but the CI check is failing,

1. Check for hidden checklists in your PR description

2. Toggle the github label checklist-action-run on/off to re-run the checklist CI.

[davydov-d]

please bump version in Dockerfile and metadata.yaml, also add a record in the changelog

[octavia-squidington-iii]

source-s3 test report (commit 327b0fa50a) - ✅

⏲️ Total pipeline duration: 23mn22s

Step	Result
Validate airbyte-integrations/connectors/source-s3/metadata.yaml	✅
Connector version semver check	✅
QA checks	✅
Code format checks	✅
Connector package install	✅
Build source-s3 docker image for platform linux/x86_64	✅
Unit tests	✅
Integration tests	✅
Acceptance tests	✅

🔗 View the logs here

Please note that tests are only run on PR ready for review. Please set your PR to draft mode to not flood the CI engine and upstream service on following commits.
You can run the same pipeline locally on this branch with the airbyte-ci tool with the following command

airbyte-ci connectors --name=source-s3 test