Update Sphinx to v7+ for Python 3.13+ compatibility.

Sphinx 4.2.0 uses the imghdr module which was removed in Python 3.13. Updated to Sphinx >=7.0.0 which is compatible with modern Python versions. Also updated sphinx_rtd_theme to use >= instead of == for better compatibility.

Author: RoryBarnes

environment.yml

@@ -14,10 +14,10 @@ dependencies:
      - pytest-dependency>=0.5.1
      - pytest-env>=0.6.2
      - pytest-cov>=2.11.1
-     - sphinx==4.2.0
+     - sphinx>=7.0.0
      - breathe>=4.30.0
      - sphinxcontrib-bibtex>=2.2.0
      - coverage>=5.5
      - argparse>=1.4
      - h5py>=3.1
-     - sphinx_rtd_theme==1.0.0
+     - sphinx_rtd_theme>=1.0.0