Add PR check and PyPi publish workflow

[upfixer]

Description

Add github workflow:

• PR run test and lint check
• publish to PyPI

Type of change

• New feature (non-breaking change which adds functionality)

How Has This Been Tested?

• PR check workflow test run https://github.com/oracle-samples/oci-openai/actions/runs/21187778692
• publish to test pypi workflow run https://github.com/oracle-samples/oci-openai/actions/runs/21187778695 (failed due to package already exist)

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules