Add doctests to interpolation_search.py

[Ihor-Pryyma]

Describe your change:

Contributes to #9943

• Add an algorithm?
• Fix a bug or typo in an existing algorithm?
• Add or change doctests? -- Note: Please avoid changing both code and tests in a single pull request.
• Documentation change?

Checklist:

• I have read CONTRIBUTING.md.
• This pull request is all my own work -- I have not plagiarized.
• I know that pull requests will not be merged if they fail the automated tests.
• This PR only changes one algorithm file. To ease review, please open separate PRs for separate algorithms.
• All new Python files are placed inside an existing directory.
• All filenames are in all lowercase characters with no spaces or dashes.
• All functions and variable names follow Python naming conventions.
• All function parameters and return values are annotated with Python type hints.
• All functions have doctests that pass the automated testing.
• All new algorithms include at least one URL that points to Wikipedia or another similar explanation.
• If this pull request resolves one or more open issues then the description above includes the issue number(s) with a closing keyword: "Fixes #ISSUE-NUMBER".

[Abonimohan]

Line 11-12 please check it out

[imSanko]

value not in ("#", ""). Use a set if the elements are hashable.

[Ihor-Pryyma]

value not in ("#", ""). Use a set if the elements are hashable.

but that file is not in my PR

[cclauss]

Suggested change

	>>> interpolation_search([1, 2, 3, 4, 5], 6)
	>>> interpolation_search([], 1)
	>>> interpolation_search([1, 2, 3, 4, 5], 6) is None
	True
	>>> interpolation_search([], 1) is None
	True

Please repeat below.

[Ihor-Pryyma]

fixed

[cclauss]

web_programming/emails_from_url.py was fixed in a separate pull request.

[imSanko]

Looks good to be @cclauss will let know better to move forward with this.

[cclauss]

Thanks!