Update version of 1.5.3, update Copyright

[apcraig]

PR checklist

• Short (1 sentence) summary of your PR:
  Update version of 1.5.3, update Copyright
• Developer(s):
  apcraig
• Suggest PR reviewers from list in the column to the right.
• Please copy the PR test results link or provide a summary of testing completed below.
  No testing done, only comments changed, will do comprehensive testing for release
• How much do the PR code changes differ from the unmodified code?
  • bit for bit
  • different at roundoff level
  • more substantial
• Does this PR create or have dependencies on CICE or any other models?
  • Yes
  • No
• Does this PR add any new test cases?
  • Yes
  • No
• Is the documentation being updated? ("Documentation" includes information on the wiki or in the .rst files from doc/source/, which are used to create the online technical docs at https://readthedocs.org/projects/cice-consortium-cice/.)
  • Yes
  • No, does the documentation need to be updated at a later time?
    • Yes
    • No
• Please document the changes in detail, including why the changes are made. This will become part of the PR commit log.

This updates the model version from 1.5.2 to 1.5.3 in preparation for the next release. This also updates the copyright to 2026.

[apcraig]

I update the zenodo copyright, I don't think we need to add any other authors. Do we need any zenodo changes?