Relax tolerances when testing HinderedRotor.get_enthalpy()

[rwest]

Motivation or Problem

When testing HinderedRotor.get_enthalpy() method using a Fourier series potential in the quantum limit it calls get_enthalpy which, in the quantum limit, calls solve_schrodinger_equation, which calls scipy.linalg.eig_banded(H, lower=True, eigvals_only=True, overwrite_a_band=True), which apparently now gives a subtly different answer, and the unit test fails.

======================================================================
FAIL: Test the HinderedRotor.get_enthalpy() method using a Fourier series
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/runner/work/RMG-Py/RMG-Py/rmgpy/statmech/torsionTest.py", line 292, in test_get_enthalpy_quantum_fourier
    self.assertAlmostEqual(h_exp, h_act, delta=1e-3 * h_exp)
AssertionError: 1367.5252765416 != 1368.9776611328125 within 1.3675252765416002 delta (1.4523845912124216 difference)

There's a lengthy discussion in #1682 trying to track down the possibility of a bug due to some gnarly numerical issues. In the end they increased the tolerance on a unit test.

Since nothing has changed recently relating to this code, except some C++ libraries on conda-forge that are used on the test runners, I propose taking the same approach, and relaxing the tolerance on the test. Maybe we're more accurate now than we used to be 🤷

Description of Changes

The tolerance in test_get_enthalpy_quantum_fourier was 0.1%. It's now 0.2%.

Testing and Reviewer Tips

There's a deep dive at #1682.
The unit tests now pass on this branch.

[mjohnson541]

Yeah, I think this is fine.

[codecov]

Codecov Report

Merging #2457 (cd2b77a) into main (d57bb10) will decrease coverage by 0.03%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main    #2457      +/-   ##
==========================================
- Coverage   48.14%   48.12%   -0.03%     
==========================================
  Files         110      110              
  Lines       30629    30629              
  Branches     7989     7989              
==========================================
- Hits        14747    14739       -8     
- Misses      14353    14363      +10     
+ Partials     1529     1527       -2     

see 3 files with indirect coverage changes

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