binary-search-tree: add angle brackets when calling constructor

[FridaTveit]

Since the BST class uses generics it should be constructed using angle brackets. For example:

BST<Integer> binarySearchTree = new BST<>();

This is done sometimes in BSTTest but not always. It should be done everywhere where a BST object is created in BSTTest.

[stkent]

(Reminder that this exercise is pending review for use of generics per #230 also.)

[ribhav-pahuja]

@FridaTveit , I would like to contribute to this.

[Smarticles101]

@ribhav-pahuja Feel free to tackle this! 👍

[FridaTveit]

Yes, like @Smarticles101 said, feel free to work on it :)

[FridaTveit]

Fixed in PR #842. Thanks @szielinski! :)

I'm sorry if you were still working on it @ribhav-pahuja. I forgot about your comment when merging the PR, sorry. There should be lots of other good-first-patch issues you can work on though. Let me know if you have any problems finding any :)