Bump numpy from 1.20.2 to 1.21.0 in /utils/dicom_converter (#4243)

Bumps [numpy](https://github.com/numpy/numpy) from 1.20.2 to 1.21.0.
- [Release notes](https://github.com/numpy/numpy/releases)
- [Changelog](https://github.com/numpy/numpy/blob/main/doc/HOWTO_RELEASE.rst.txt)
- [Commits](https://github.com/numpy/numpy/compare/v1.20.2...v1.21.0)

---
updated-dependencies:
- dependency-name: numpy
  dependency-type: direct:production
...
Signed-off-by: Ndependabot[bot] <support@github.com>
Co-authored-by: Ndependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: NNikita Manovich <nikita.manovich@intel.com>

utils/dicom_converter/requirements.txt

-numpy==1.20.2
+numpy==1.21.0
 Pillow==9.0.0
 pydicom==2.1.2
 tqdm==4.60.0