Fixes #500

From what I witnessed, black does not flag use of deprecated typing.T types, e.g., typing.Dict instead of dict, but ruff does with the rule UP006.

On a tangential note, maybe it'll be worth integrating a stronger linter like ruff into the CI pipeline at some point. We probably don't want to enforce all of the default rules to avoid making contributing overly painful, but for specific things I believe it might be worth having.

Find offending lines

ruff check --target-version "py39" --select "UP006"

(See ruff.txt for the output)

Fix

Apparently, ruff is able to fix the code automatically but it requires using the option --unsafe-fixes so I'm not sure if it can be trusted. It's what I've used for this PR.

ruff check --unsafe-fixes --fix --target-version "py39" --select "UP006"

After doing that, there remained occurrences of the deprecated types 1) in imports, and 2) in docstrings. I got rid of them both manually using this command to find their presence:

git grep -w -e "Dict" -e "List" -e "Tuple"

ruff.txt (download, excerpt below)

deepinv/datasets/cmrxrecon.py:108:19: UP006 Use `tuple` instead of `Tuple` for type annotation
    |
106 |         mask_generator: Optional[BaseMaskGenerator] = None,
107 |         transform: Optional[Callable] = None,
108 |         pad_size: Tuple[int, int] = (512, 256),
    |                   ^^^^^ UP006
109 |         noise_model: NoiseModel = None,
110 |     ):
    |
    = help: Replace with `tuple`

deepinv/datasets/cmrxrecon.py:171:10: UP006 Use `dict` instead of `Dict` for type annotation
    |
169 |     def _retrieve_metadata(
170 |         self, fname: Union[str, Path, os.PathLike]
171 |     ) -> Dict[str, Any]:
    |          ^^^^ UP006
172 |         """Open file and retrieve metadata
    |
    = help: Replace with `dict`

(Truncated)

Found 90 errors.
No fixes available (90 hidden fixes can be enabled with the `--unsafe-fixes` option).

Checks to be done before submitting your PR

• python3 -m pytest tests/ runs successfully.
• black . runs successfully.
• make html runs successfully (in the docs/ directory).
• Updated docstrings related to the changes (as applicable).
• Added an entry to the CHANGELOG.rst.