Add unit tests for simple_utils.py utility functions

[coderabbitai]

Description

This is a follow-up task from PR #1 to add comprehensive unit tests for the utility functions introduced in simple_utils.py.

Background

The following functions were added without unit tests and require test coverage:

• reverse_string(text): Function that reverses a string
• count_words(sentence): Function that counts words in a sentence
• celsius_to_fahrenheit(celsius): Function that converts Celsius to Fahrenheit

References

• Original PR: Create simple_utils.py brian8232/help-center#1
• Requested by: @brian8232

Acceptance Criteria

• Add unit tests for reverse_string function with various test cases
• Add unit tests for count_words function including edge cases
• Add unit tests for celsius_to_fahrenheit function with various temperature values
• Ensure all tests pass successfully
• Achieve adequate code coverage for the module