A program which finds the diameter of a binary tree.

Description

Please include a summary of the changes you have made in regard with this issue.

Fixes #(issue number)

Type of change

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[ ] I have read the contribution guidelines before making this PR.
[ ] My code follows the style guidelines of this project
[ ] I have performed a self-review of my own code
[ ] I have commented in my code, particularly in hard-to-understand areas
[ ] I have made corresponding changes to the documentation (Language folder or any other readme instructed to)
[ ] My changes generates no new warnings
[ ] I have added tests that prove my fix is effective or that my feature works