Allow estimate to run without redshift

[raphaelshirley]

Closes #49

Allow running of estimate without redshift

Code Quality

• [x] My code follows the code style of this project
• [ ] I have written unit tests or justified all instances of #pragma: no cover; in the case of a bugfix, a new test that breaks as a result of the bug has been added
• [x] My code contains relevant comments and necessary documentation for future maintainers; the change is reflected in applicable demos/tutorials (with output cleared!) and added/updated docstrings use the NumPy docstring format
• [x] Any breaking changes, described above, are accompanied by backwards compatibility and deprecation warnings

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 0% with 5 lines in your changes are missing coverage. Please review.

Project coverage is 46.03%. Comparing base (822f486) to head (03ba798).

Files	Patch %	Lines
src/rail/estimation/algos/lephare.py	0.00%	5 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #50 +/- ## ========================================== - Coverage 47.15% 46.03% -1.13% ========================================== Files 2 2 Lines 123 126 +3 ========================================== Hits 58 58 - Misses 65 68 +3 ```

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