Allow flexible ufm params

[srmnitc]

This pull request refactors the Liquid class in calphy/liquid.py to improve code readability and maintainability by reformatting multi-line code blocks and enhancing consistency in string formatting. The changes primarily involve the restructuring of method implementations and minor adjustments to logic.

Code readability improvements:

• Reformatted multi-line method calls and string formatting for better readability, such as in __init__, melt_structure, run_averaging, and run_integration methods. [1] [2] [3] [4]

Logical enhancements:

• Updated logic to use consistent string formatting (e.g., replacing single quotes with double quotes in run_averaging and run_integration). [1] [2]
• Improved the parameterization of the Uhlenbeck-Ford model in thermodynamic_integration by replacing hardcoded values with configurable attributes.

Minor cleanup:

• Removed unnecessary blank lines and comments for cleaner code structure. [1] [2]