Update pydicom to version 3

[p-j-smith]

Description

Part of #665

• update to pydicom==3.0.2. This also means when need to update the versions of deid and dicom-analyzer
• write_like_original=False has been removed in pydicom 3. Use enforce_file_format=True instead
• we need to pass implicit_vr=True and little_endian=True as arguments when saving a Dataset, rather than setting them as attributes
• make pixel_data np.uint16 to correspond to the BitsAllocated=16 tag we set when generating the test dataset, otherwise pydicom 3 raises a warning, which would make test_anonymise_and_validate_dicom fail as we check there are no warnings in the logs

Type of change

Please delete options accordingly to the description.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

Suggested Checklist

• I have performed a self-review of my own code.
• I have made corresponding changes to the documentation.
• My changes generate no new warnings.
• I have commented my code, particularly in hard-to-understand areas.
• I have passed on my local host device. (see further details at the CONTRIBUTING document)
• Make sure your branch is up-to-date with main branch. See CONTRIBUTING for a general example to syncronise your branch with the main branch.
• I have requested review to this PR.
• I have addressed and marked as resolved all the review comments in my PR.
• Finally, I have selected squash and merge

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 88.37%. Comparing base (301bc9d) to head (8c4fc61).

Additional details and impacted files

@@                     Coverage Diff                      @@
##           paul/665-uv-lock-format     #671       +/-   ##
============================================================
+ Coverage                    67.31%   88.37%   +21.05%     
============================================================
  Files                           56       81       +25     
  Lines                         2408     3956     +1548     
============================================================
+ Hits                          1621     3496     +1875     
+ Misses                         787      460      -327     

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