fix import mmrazor error in mmcls test

[RunningLeon]

tests/test_codebase/test_mmcls/test_classification.py:68: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

self = <mmdeploy.codebase.mmcls.deploy.classification.Classification object at 0x7f67c80f4150>, model_checkpoint = None
cfg_options = None, kwargs = {}

    def init_pytorch_model(self,
                           model_checkpoint: Optional[str] = None,
                           cfg_options: Optional[Dict] = None,
                           **kwargs) -> torch.nn.Module:
        """Initialize torch model.
    
        Args:
            model_checkpoint (str): The checkpoint file of torch model,
                Default: None.
            cfg_options (dict): Optional config key-pair parameters.
    
        Returns:
            nn.Module: An initialized torch model generated by OpenMMLab
                codebases.
        """
        if self.from_mmrazor:
>           from mmrazor.apis import init_mmcls_model as init_model
E           ModuleNotFoundError: No module named 'mmrazor'

mmdeploy/codebase/mmcls/deploy/classification.py:99: ModuleNotFoundError

Motivation

Fix import mmrazor error in mmcls test.

Modification

Skip test if mmrazor is not installed.

BC-breaking (Optional)

None

Use cases (Optional)

If this PR introduces a new feature, it is better to list some use cases here, and update the documentation.

Checklist

1. Pre-commit or other linting tools are used to fix the potential lint issues.
2. The modification is covered by complete unit tests. If not, please add more unit tests to ensure the correctness.
3. If the modification has a dependency on downstream projects of a newer version, this PR should be tested with all supported versions of downstream projects.
4. The documentation has been modified accordingly, like docstring or example tutorials.

[grimoire]

LGTM