Fix Dependencies. Update Packages and Metadata

[MGross21]

This pull request introduces several improvements to the Universal Robots (UR) support in the armctl library, enhances dependency management, and makes minor workflow optimizations. The most significant changes are the move of UR support to an optional dependency, improved error handling for missing UR requirements, and updates to the CI workflow for better performance and clarity.

Universal Robots (UR) support and dependency management:

• Universal Robots support is now an optional dependency (armctl[ur]), and the main dependency list no longer includes urrtde by default. Installation instructions in the README.md have been updated to reflect this change. [1] [2]
• Improved error handling for missing UR dependencies: importing UR RTDE modules now provides a clear error message instructing users to install armctl[ur] if the urrtde package is not found. [1] [2]

Build and workflow improvements:

• Updated the build system requirement to uv_build>=0.11.2,<0.12 and changed the license declaration for improved compliance. [1] [2]
• The CI workflow no longer installs all extras by default, reflecting the new optional dependency structure, and adds environment variables to optimize Python execution and bytecode handling. [1] [2] [3]