Use PEP 448 unpacking to concatenate iterables

[Aarni Koskela]

​https://peps.python.org/pep-0448/ (shipped in Python 3.5) adds support for unpacking in tuple/list displays.

This is faster in micro-benchmarks (every little helps), more concise, arguably more readable, and avoids certain classes of bugs where users pass in tuples where Django expects lists and vice versa (see e.g. ​https://github.com/django/django/pull/15270).

Some instances of this can be automatically found and fixed with the Ruff linter's RUF005 rule (​https://docs.astral.sh/ruff/rules/collection-literal-concatenation/).