ludwig-cf/ludwig: Ludwig-0.20.0

Version 0.20.0 Release date: July 2023 Changes include: IMPORTANT: The input file can no longer be specified as a command line argument. It must be called "input" in the current directory. The electrokinetics sector has been updated and information is available at https://ludwig.epcc.ed.ac.uk/tutorials/electrokinetics/electrokinetics.html A D3Q27 model is available Added coverage via https://about.codecov.io/ The free energy is now reported at t = 0 for the initial state. An extra "first touch" option has been added. For details, see https://ludwig.epcc.ed.ac.uk/inputs/parallel.html Various minor changes and code quality improvements