#37 Remove `ttkthemes`

[ian-young]

Removed ttkthemes

Description

Removed ttkthemes for easier installation of all the modules.

Fixes #37

How Has This Been Tested?

• [x] customer_sheet_1.csv
• [x] customer_sheet_2.csv
• [x] customer_sheet_3.csv
• [x] customer_sheet_4.csv
• [x] customer_sheet_5.csv
• [x] customer_sheet_6.csv
• [x] customer_sheet_7.csv
• [x] customer_sheet_8.csv
• [x] customer_sheet_9.csv
• [x] customer_sheet_10.csv
• [x] customer_sheet_11.csv

Checklist

• [x] My code follows the PEP8style guidelines.
• [x] I have performed a self-review of my code
• [x] I have commented my code, particularly in hard-to-understand areas
• [x] I have made corresponding changes to the documentation
• [x] My changes generate no new warnings
• [x] I have added tests that prove my fix is effective or that my feature works
• [x] New and existing unit tests pass locally with my changes
• [x] Any dependent changes have been merged and published in downstream modules