Fix API version configuration: restore v1 URL path and update header to 1.2.0

[Copilot]

Aims of this PR

Fixes accidental API version misconfiguration. The SDK was using 1.2 for both URL routing and the X-Api-Version header, but should use v1 for URL paths and 1.2.0 for the header.

Changes:

• LATEST_API_VERSION: "1.2" → "1.2.0" (sets X-Api-Version header)
• Default version parameter in Client and AsyncClient: "1.2" → "v1" (URL path component)

Result:

import autumn

client = autumn.Client(token="...")
# URLs: https://api.useautumn.com/v1/check
# Headers: X-Api-Version: 1.2.0

Checklist

• Have code changes been tested?
• Has documentation been updated?
• Does this PR fix an issue?
• Does this PR make breaking changes?

Additional context
The base URL https://api.useautumn.com remains unchanged. The /v1 route version is stable; the X-Api-Version header controls actual API behavior and schema versions.

Original prompt

Can you help me fix a bug where recently we accidentally changed the 'latest api version' from 1.4 to 1.2.

In our API, there are two versions: one in the route, and one in the actual functional api.

https://api.useautumn.com/v1/ is ALWAYS the base url. we won't be changing it any time soon.

However, the X-Api-Version header is the ACTUAL version that changes response schemas and request schemas and functionality. Please make the base latest version X-Api-Version: 1.2.0, and return the version in the URL to v1

Thank you!

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Summary by cubic

Fixes API versioning mismatch by restoring the URL to /v1 and setting the default X-Api-Version to 1.2.0. Aligns request/response schemas to the intended latest functional API version.

• Bug Fixes
  • Restored base route to https://api.useautumn.com/v1/.
  • Set global default X-Api-Version header to 1.2.0.

^{Written for commit 4bacebc. Summary will update on new commits.}

[cubic-dev-ai]

No issues found across 3 files