Use `pydicom.dcmread()` instead of `pydicom.read_file()`

[jwodder]

read_file() was deprecated in pydicom v2.2.0 and will be removed in v3.0. Code should instead use dcmread(), which has been an alias of read_file() since pydicom v1.0.0.

[codecov[bot]]

Codecov Report

Patch coverage: 75.00% and no project coverage change.

Comparison is base (2c6d228) 81.48% compared to head (37d5973) 81.48%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #668 +/- ## ======================================= Coverage 81.48% 81.48% ======================================= Files 41 41 Lines 3900 3900 ======================================= Hits 3178 3178 Misses 722 722 ``` | [Impacted Files](https://codecov.io/gh/nipy/heudiconv/pull/668?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=nipy) | Coverage Δ | | |---|---|---| | [heudiconv/heuristics/multires\_7Tbold.py](https://codecov.io/gh/nipy/heudiconv/pull/668?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=nipy#diff-aGV1ZGljb252L2hldXJpc3RpY3MvbXVsdGlyZXNfN1Rib2xkLnB5) | `14.28% <0.00%> (ø)` | | | [heudiconv/tests/test\_regression.py](https://codecov.io/gh/nipy/heudiconv/pull/668?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=nipy#diff-aGV1ZGljb252L3Rlc3RzL3Rlc3RfcmVncmVzc2lvbi5weQ==) | `93.25% <ø> (ø)` | | | [heudiconv/bids.py](https://codecov.io/gh/nipy/heudiconv/pull/668?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=nipy#diff-aGV1ZGljb252L2JpZHMucHk=) | `90.51% <100.00%> (ø)` | | | [heudiconv/dicoms.py](https://codecov.io/gh/nipy/heudiconv/pull/668?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=nipy#diff-aGV1ZGljb252L2RpY29tcy5weQ==) | `86.10% <100.00%> (ø)` | | | [heudiconv/tests/test\_dicoms.py](https://codecov.io/gh/nipy/heudiconv/pull/668?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=nipy#diff-aGV1ZGljb252L3Rlc3RzL3Rlc3RfZGljb21zLnB5) | `86.04% <100.00%> (ø)` | | Help us with your feedback. Take ten seconds to tell us [how you rate us](https://about.codecov.io/nps?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=nipy). Have a feature suggestion? [Share it here.](https://app.codecov.io/gh/feedback/?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=nipy)

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[yarikoptic]

Thank you!

[github-actions[bot]]

:rocket: PR was released in v0.13.0 :rocket: