Feature/stochastic process test

Tests for Stochastic Process module

Provides 85% code coverage across the module

How Has This Been Tested?

Unit tests for all the methods in Stochastic Process module have been added

Screenshots (if appropriate):

Types of changes

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[ ] Bug fix (non-breaking change which fixes an issue)
[ ] New feature (non-breaking change which adds functionality)
[ ] Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

Go over all the following points, and put an x in all the boxes that apply. If you're unsure about any of these, don't hesitate to ask. We're here to help!

[x] My code follows the code style of this project.
[ ] My change requires a change to the documentation.
[ ] I have updated the documentation accordingly.
[x] I have read the CONTRIBUTING document.
[x] I have added tests to cover my changes.
[x] All new and existing tests passed.

SURGroup / UQpy

Feature/stochastic process test #121

How Has This Been Tested?

Screenshots (if appropriate):

Types of changes

Checklist: