Add indian holidays

[webmavensteam]

Contributing a new country ?

• Have you checked to ensure there aren't other open Pull Requests for the same country?

1. Create a new class in the Countries directory. It should extend the Country class.
2. Add a test for the new country in the tests directory.
3. Run the tests so a snapshot gets created.
4. Verify the result in the newly created snapshot is correct.

[webmavensteam]

@Nielsvanpach Our test cases failed because of the below test.

We have added a fix to it.

Also, we have a PHPSTAN error for the below file.

Would you like for us to fix that file also?

[webmavensteam]

@Nielsvanpach We have added fix for above phpstan issue.

[Nielsvanpach]

Thanks!