Fix test failures, improve CI diagnostics & bump package versions

[pangpang20]

Description

This PR delivers a stable v1.0.4 release of the gaussdb-python driver by resolving the three recently reported test-related issues (#25, #26, #27) and introducing several quality-of-life improvements to CI, documentation, and test reliability.

Key highlights:

• Fixed PYTHONPATH misconfiguration that caused AttributeError: module 'gaussdb' has no attribute 'version' when running the driver locally.
• Resolved sporadic unit test failures in test_range (insufficient privileges) and test_adapt (Faker returning None for binary types).
• Added wal_level detection to automatically skip logical decoding tests when the database is not configured for logical replication.
• Improved CI workflows with DNS/Python environment diagnostics and suppression of noisy ResourceWarnings.
• Updated README and sub-package documentation with correct multi-module PYTHONPATH examples.
• Bumped gaussdb, gaussdb_pool, and isort_gaussdb versions in preparation for release.

Closes #25, closes #26, closes #27.

Changes Made

Documentation

• Updated README.rst, gaussdb/README.rst, gaussdb_pool/README.rst, and tools/isort-gaussdb/README.rst to use correct backticks for license file links and clarified local development instructions.
• Fixed all local development examples to set PYTHONPATH to both gaussdb and gaussdb_pool submodules, preventing import/attribute errors.

Test fixes & robustness

• Added get_wal_level() helper and automatic skip of logical decoding tests when wal_level != logical.
• Fixed schema cleanup in range/composite tests by forcing owner to root and using fully qualified type names.
• Improved Faker binary matcher in tests/fix_faker.py to accept None/empty values.
• Added proper blank lines and import order fixes for better black/isort compliance.
• Skipped unsupported composite/range type tests explicitly on GaussDB.

Testing

• All unit tests now pass consistently on both standard and SSL CI runners.
• Logical decoding tests are automatically skipped on databases without wal_level = logical.
• Range and composite type tests correctly clean up schemas and skip where unsupported.
• Local development setup verified with the updated PYTHONPATH instructions (no more AttributeError on gaussdb.version).
• SSL workflow diagnostics confirmed correct resolution of DNS and async resolver environment.