fix: added a plt.close() to the plotting function

[taddyb]

Issue Addressed

Closes opened plots

Description

Fixes #40

Type of Change

• 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 not work as expected)
• Code cleanup/refactor
• Documentation update

Other (please specify):

Checklist

• Branch is up to date with master
• Updated tests or added new tests
• Tests & pre-commit hooks pass
• Updated documentation (if applicable)
• Code follows established style and conventions

[taddyb]

Merging since this is a 1 line change