test_SPDHG_vs_PDHG_explicit test is unreliable

[lauramurgatroyd]

Description

In a PR where I only changed docstrings this test failed

FAIL: test_SPDHG_vs_PDHG_explicit (test_algorithms.TestSPDHG)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/usr/share/miniconda/envs/test/conda-bld/cil_1733995110980/test_tmp/Wrappers/Python/test/test_algorithms.py", line 1535, in test_SPDHG_vs_PDHG_explicit
    np.testing.assert_almost_equal(mae(spdhg.get_output(), pdhg.get_output()),
  File "/usr/share/miniconda/envs/test/conda-bld/cil_1733995110980/_test_env_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_plac/lib/python3.10/site-packages/numpy/testing/_private/utils.py", line 599, in assert_almost_equal
    raise AssertionError(_build_err_msg())
AssertionError: 
Arrays are not almost equal to 3 decimals
 ACTUAL: 0.00545253
 DESIRED: 0.0031962995

Environment

CIL master - github action for PR - action is conda (3.10, 1.23)
https://github.com/TomographicImaging/CIL/actions/runs/12293300385/attempts/1

import cil, sys
print(cil.version.version, cil.version.commit_hash, sys.version, sys.platform)