Refactor token API tests and remove unused `user_id` parameter (#6)

# Updated token API test cases to validate token creation, revocation, and verification logic comprehensively

- Removed unused imports (`socket`, `os`) from `_utils.py`
- Improved response handling by safely accessing Content-Type header with `.get()` method
- Removed `user_id` parameter from token management functions as it's no longer required by the API
- Added comprehensive token lifecycle test that validates creation, verification, and revocation
- Implemented test skipping logic with `EXPLICIT` flag instead of global `pytestmark`
- Added proper token validation checks throughout the test process

Refactor token API tests and remove unused `user_id` parameter (#6)

# Updated token API test cases to validate token creation, revocation, and verification logic comprehensively

- Removed unused imports (`socket`, `os`) from `_utils.py`
- Improved response handling by safely accessing Content-Type header with `.get()` method
- Removed `user_id` parameter from token management functions as it's no longer required by the API
- Added comprehensive token lifecycle test that validates creation, verification, and revocation
- Implemented test skipping logic with `EXPLICIT` flag instead of global `pytestmark`
- Added proper token validation checks throughout the test process

[BUG] Set default value for BACKEND_OVERRIDE environment variable

The BACKEND_OVERRIDE environment variable now defaults to an empty list if not provided. This improves reliability by avoiding potential issues with undefined values in the configuration.

[ENH] Update requirements: remove version specifiers and replace subs…

…urface dependency

TeamCity change in 'LiquidEarthPythonSdk' project: 'Release' build co…

…nfiguration settings were updated

[BUG] Set default value for BACKEND_OVERRIDE environment variable

The BACKEND_OVERRIDE environment variable now defaults to an empty list if not provided. This improves reliability by avoiding potential issues with undefined values in the configuration.

[ENH] Update requirements: remove version specifiers and replace subs…

…urface dependency

[ENH] Rename package from 'liquid_earth_api' to 'liquid_earth_sdk' an…

…d update description

[ENH] Rename package from 'liquid_earth_api' to 'liquid_earth_sdk' an…

…d update description