Update CLA URLs & Update GitHub Actions

[DhanushPillay]

This pull request updates the project's GitHub Actions workflows to use the latest versions of key actions for improved security and compatibility. Additionally, it updates the Contributor License Agreement (CLA) links in the documentation to use secure HTTPS URLs.

Workflow action version upgrades:

• Updated all uses of actions/checkout from version 2 to version 4 in .github/workflows/ci.yaml and .github/workflows/bot-pr-new.yaml for better performance and security. [1] [2] [3] [4]
• Updated all uses of actions/setup-python from version 1 to version 5 in .github/workflows/ci.yaml to ensure compatibility with the latest Python versions and features. [1] [2]

Documentation updates:

• Changed CLA links in CONTRIBUTING.md from http to https for both individual and corporate agreements to ensure secure access.