Fix various typos throughout the codebase

Found via codespell -q 3 -S ./third-party,./src/Geom -L anumber,oce,te,thes,xwindows

Checklist

[x] Source is rebased on latest upstream main so is mergeable automatically or easily merged even with confliction.
[x] Title of this PR is meaningful: e.g. "fix issue #8 geomPipeline.py -o does not work", not "fix geomPipeline.py"
[x] Commit message is meaningful: git push origin +your_branch to squash some tiny fixes for CI failures
[x] Give the maintainer the legal rights to change the open source license in the future (see wiki/Contribution.md) for details

ukaea / parallel-preprocessor