chore(deps): sdk-5393 update compatible security dependencies

[dciccale]

The SDK currently permits Requests 2.32.3 and IDNA versions affected by the credential-leak and input-processing advisories. Raise the published minimums to requests>=2.32.4,<3.0 and idna>=3.15,<4.0, and update the matching repository pins. The explicit IDNA requirement prevents Requests from resolving an older vulnerable version.

This is the Python 3.8-compatible security subset of #126. Python support remains >=3.8; the remaining dependency updates and advisories stay in SDK-5393, with Python support changes tracked separately in SDK-5392. This PR addresses Dependabot alerts #2 and #13.

Validation:

• Built the source distribution and wheel with the repository's build-tool versions; both passed twine check.
• Installed the wheel with normal dependency resolution on Python 3.8 and 3.12; all 86 repository tests passed on each version, including the real local HTTP proxy test. Confirmed the SDK imports came from the installed wheel.
• Verified the wheel metadata rejects Requests 2.32.3 and IDNA 3.14, accepts the new minimums, and preserves Requires-Python: >=3.8.0.
• Repository fatal-error lint and git diff --check passed. Regenerated requirements.txt with pip-tools 7.4.1 on Python 3.12.

Partial progress on SDK-5393. Python support changes: SDK-5392.