fix ts fe test error.

[lanluo-nvidia]

Description

Please include a summary of the change and which issue is fixed. Please also include relevant motivation and context. List any dependencies that are required for this change.

Fixes # (issue)
flashinfer = pytest.importorskip("flashinfer")
this way once pyest is run, it gives the following:
SKIPPED [1] automatic_plugin/test_flashinfer_rmsnorm.py:3: could not import 'flashinfer': No module named 'flashinfer'
with error code, which will make the CI show as red.

change to:
@unittest.skipIf(not importlib.util.find_spec("flashinfer"), "flashinfer not installed")
so that pytest will skip and show as green

Type of change

Please delete options that are not relevant and/or add your own.

• 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

Checklist:

• My code follows the style guidelines of this project (You can use the linters)
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas and hacks
• I have made corresponding changes to the documentation
• I have added tests to verify my fix or my feature
• New and existing unit tests pass locally with my changes
• I have added the relevant labels to my PR in so that relevant reviewers are notified

[peri044]

LGTM