0.29.0

perf: misc internal performance improvements (#38)

- Alias type annotations
- Use PEP 563 type annotations
- Simplify ConcurrentAsyncExecutor
- Optimize DAG building and execution by minimizing attribute access and removing redundant checks
- Don't automatically convert Scope keys to list
- Add `__slots__` to various classes w/ heavy attribute access
- Remove ConcurrentAsyncExecutor, it is not needed and can be implemented by users