Fixed string formatting styles

[eytanadler]

Purpose

PR #345 added a new feature but combined string formatting styles. This PR changes it to consistently be f strings.

Expected time until merged

Type of change

• [ ] Bugfix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (non-backwards-compatible fix or feature)
• [x] Code style update (formatting, renaming)
• [ ] Refactoring (no functional changes, no API changes)
• [ ] Documentation update
• [ ] Maintenance update
• [ ] Other (please describe)

Testing

Checklist

• [x] I have run flake8 and black to make sure the Python code adheres to PEP-8 and is consistently formatted
• [ ] I have formatted the Fortran code with fprettify or C/C++ code with clang-format as applicable
• [x] I have run unit and regression tests which pass locally with my changes
• [x] I have added new tests that prove my fix is effective or that my feature works
• [ ] I have added necessary documentation

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 66.66667% with 1 lines in your changes are missing coverage. Please review.

Project coverage is 41.47%. Comparing base (5a8c177) to head (b3ef06f).

Files	Patch %	Lines
adflow/pyADflow.py	66.66%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #347 +/- ## ======================================= Coverage 41.47% 41.47% ======================================= Files 13 13 Lines 4068 4068 ======================================= Hits 1687 1687 Misses 2381 2381 ```

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