Consider adding `asyncstdlib` by default to the dependencies in the template

[llucax]

What's needed?

asyncstdlib provide common functionality for async code that works with async code and it is not present in Python's stdlib yet, like an async filter, map, etc.

Proposed solution

Add https://pypi.org/project/asyncstdlib/ as a dependency by default.

Additional context

Coming from:

• Support filtering the messages on a receiver frequenz-channels-python#303