Build cleanup

[c8y3]

Restructuring of the build and packaging of the directory:

• set up continuous integration (with automatic release on tag)
• use uv to manage dependencies, package and run commands
• use ruff to check code
• set python version in .python-version file
• documented development commands in CONTRIBUTING.md
• renamed directory source into src to follow standard conventions
• added missing dependency requests~=2.31.0
• updated some dependencies
• fixed ruff warnings (with the default ruff configuration)
• made a more precise fix for Fix AttributeError in PictureGlobals when alignment value is string #4 (since the dependencies are now precisely set)