Adding Pi calculation algorithms for Pi Day

[aidnyu]

This PR introduces two Pi calculation implementations with doc tests:

• Adding Chudnovsky algorithm implementation (chudnovsky_algorithm.mojo)
• Adding Leibniz formula for Pi calculation (leibniz_pi_formula.mojo)

• [x] I have performed a self-review of my code
• [x] My code follows the style guidelines of this project
• [x] I have added tests that prove my fix is effective or that my feature works
• [x] New and existing unit tests pass locally with my changes
• [x] Comments in areas I changed are up to date
• [x] I have added comments to hard-to-understand areas of my code