style: Change "serialise" etc to "serialize" etc.

[cqc-alec]

Did: git grep -l -i 'serialis' | xargs sed -i 's/erialis/erializ/g'

The "-ize" spelling is already used much more often, so let's be consistent.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 86.98%. Comparing base (3e4ac18) to head (e68d1c0).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #1251 +/- ## ======================================= Coverage 86.98% 86.98% ======================================= Files 102 102 Lines 19108 19108 Branches 17015 17015 ======================================= Hits 16622 16622 Misses 1709 1709 Partials 777 777 ``` | [Flag](https://app.codecov.io/gh/CQCL/hugr/pull/1251/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=CQCL) | Coverage Δ | | |---|---|---| | [python](https://app.codecov.io/gh/CQCL/hugr/pull/1251/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=CQCL) | `91.16% <ø> (ø)` | | | [rust](https://app.codecov.io/gh/CQCL/hugr/pull/1251/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=CQCL) | `86.47% <100.00%> (ø)` | | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=CQCL#carryforward-flags-in-the-pull-request-comment) to find out more.

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[cqc-alec]

👍 It looks like we only used UK spelling on docs. Was all the code US-style?

We should maybe decide to use either UK or US spelling everywhere, and add it to DEVELOPMENT.md.

It's not quite as simple as US/UK style: there are different UK styles. See for example https://academic.oup.com/pages/authoring/books/preparing-your-manuscript/house-style#oup .

I wouldn't be opposed to adopting (and documenting) a house style, such as the OUP one, but this should perhaps be a larger conversation between software projects.