v0.6.0

Changes:

• Support python 3.12 (PR #93)
• Support pyright and improve typing in general (PR #99)
• Move from setup.* to pyproject.toml (PR #101, #102, #103, #110)
• Add typing to aiostream.test_utils (PR #104)
• Make operators a singleton object instead of a class (PR #106)
• Add sources operator to fix a breaking change in v0.5.x (PR #108, issue #95)

Thanks to @hf-kklein for the valuable contributions :)