docs: document client_protocol_version in connection parameters table

[reginaldalfret]

Description

This PR documents the client_protocol_version connection parameter in the Connection Parameters table in README.rst, and provides a code snippet in the Client Transfer Protocol section demonstrating how to pass client_protocol_version.

Motivation and Context

Resolves #276

The Client Transfer Protocol section in README.rst states:

If necessary, the requested transfer protocol can be modified via the client_protocol_version parameter of redshift_connector.connect(...). Please see the Connection Parameters table for more details.

However, client_protocol_version was missing from the Connection Parameters table. This change adds the parameter name, type (int), description with supported values (0, 1, 2), default value (2), and required status (No).

Testing

• Validated table formatting and column alignments in README.rst.
• Verified no trailing whitespace or lint issues with git diff --check.
• Ran unit tests with pytest -c setup.cfg --ignore=test/performance --ignore=test/integration test/unit (2041 passed, 38 skipped).

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)

Checklist

• Commit messages follow Conventional Commit Specification
• I have read the README document
• I have run all unit tests using pytest test/unit and they are passing.

License

• By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.