test: test Node.js 25 in CI

[cjihrig]

Which problem is this PR solving?

Node 25 has been released, but is not tested in the CI.

Fixes # N/A

Short description of the changes

This commit adds Node 25 to the CI.

Type of change

• New feature (non-breaking change which adds functionality)

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce. Please also list any relevant details for your test configuration

• Ran the test suite locally on Node 25

Checklist:

• Followed the style guidelines of this project
• Unit tests have been added
• Documentation has been updated

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 95.01%. Comparing base (a93b1dc) to head (283d568).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #6019   +/-   ##
=======================================
  Coverage   95.01%   95.01%           
=======================================
  Files         313      313           
  Lines        8799     8799           
  Branches     1888     1888           
=======================================
  Hits         8360     8360           
  Misses        439      439           

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[JacksonWeber]

The README.md claims that "Only Node.js Active or Maintenance LTS versions are supported", and Node.js v25 is neither of those. I'm not opposed to adding it to the CI necessarily, but this may give the impression that we "support" a runtime that we don't claim to.

[cjihrig]

I think it's good to test on the latest version. Node 25 in particular came with a bunch of breaking changes. It seems like a good idea to understand how those might impact the library since Node 26 will still include those breaking changes, and probably new ones.

That statement in the README is already a bit inaccurate anyway since Node 18 is supported but it has been EOL for some time now 😄