PB-2758: Bump idna from 3.10 to 3.15

[cjfuller-dev]

Dependency bump of idna from 3.10 to 3.15. idna is a transitive dependency, so only poetry.lock changes; pyproject.toml is untouched.

Checks

(these are Claude assisted - asked to go through changelog)

Reviewed the changelog for 3.11–3.15. Nothing in it touches how this client uses the library:

• 3.11/3.12: Unicode data updates (16.0.0, then 17.0.0). Only affects encoding of edge-case internationalised domain names; our resource endpoints are plain ASCII hostnames.
• 3.12: transitional argument deprecated and lazy-loading added. We never call idna directly, so the deprecation cannot reach us, and lazy-loading is a minor import-time improvement.
• 3.13: Single codepoint classification fix (U+A7F1).
• 3.14/3.15: Oversize inputs (labels/domains beyond DNS length limits) are now rejected up-front rather than processed. This is the only behavioural change of note - it only affects hostnames that were already invalid per DNS length rules, so no impact here.
• Minimum Python is now 3.8 (was 3.6), well below what this project requires.

Testing

• Full test suite passes against the updated lock (35 passed).

[cariad]

Ta for this! To verify, I:

1. Configured minimalUpdate to false.
2. Regenerated the client.
3. Ran the generated unit tests against the generated client.

[cjfuller-dev]

Ta for this! To verify, I:

1. Configured `minimalUpdate` to `false`.

2. Regenerated the client.

3. Ran the generated unit tests against the generated client.

Thanks!