Zswag

Maintenance release with various C++ usability improvements:

- [x] Compatibility with zserio >= 2.6.0
- [x] Added `ZSWAG_BUILD_WHEELS` and `ZSWAG_KEYCHAIN_SUPPORT` compile switches
- [x] Upgraded to latest [`zserio-cmake-helper`](https://github.com/klebert-engineering/zserio-cmake-helper)

Release dedicated to turn the log message for a missing `HTTP_SETTINGS_FILE` from error to debug-level.

This release introduces the folllowing new features and bugfixes:

- [x] Transition to official zserio-based C++ reflection for OpenAPI client [71] 🪞
- [x] Refactored log output based on `spdlog` - logging can be controlled using the environment variable values `HTTP_LOG_LEVEL=debug` for detailed output, and `HTTP_LOG_FILE=path` to log to a file. [68] 📝
- [x] Expanded abilities for `zswag.gen` - you can now control the OpenAPI generator output with a config file and pass detailed parameter placement instructions. No more need for hand-adjusting the generated YAML! [69] 🦥

This release introduces the folllowing new features and bugfixes:

- [x] Support for OpenAPI authentication schemes (http basic/bearer, apiKey in cookie/header/query). Credentials can be passed either programatically or through the HTTP_SETTINGS_FILE. 🔐
- [x] We added an API for HTTP settings, also covering headers and query parameters to pass credentials. 🗝️
- [x] Fixed `application/x-zserio-object` MIME type usage. 🐛 [52]
- [x] Much more verbose error messages in the OpenAPI parser. 📝
- [x] Removed support for HTTP patch. 🚫
- [x] Support for the OpenAPI `in=header` parameter location. 🤯

This patch release improves the dependency requirements to allow future versions of zserio and disallow older versions of pyzswagcl.

This release fixes a CI issue for Windows, building artifacts in Release mode instead of the default Debug mode.