[Fix] make category_id in CocoWholeBodyDataset as numpy.array

[zgjja]

Motivation

parse_data_info() in class CocoWholeBodyDataset will return category_id as a List, making the transform() in class FilterAnnotations fails to indexing like a np.array.

Modification

make category_id as a numpy.array, just like what in class BaseCocoStyleDataset does.

Checklist

Before PR:

• I have read and followed the workflow indicated in the CONTRIBUTING.md to create this PR.
• Pre-commit or linting tools indicated in CONTRIBUTING.md are used to fix the potential lint issues.
• Bug fixes are covered by unit tests, the case that causes the bug should be added in the unit tests.
• New functionalities are covered by complete unit tests. If not, please add more unit tests to ensure correctness.
• The documentation has been modified accordingly, including docstring or example tutorials.

After PR:

• CLA has been signed and all committers have signed the CLA in this PR.

[CLAassistant]

All committers have signed the CLA.