[Fix] Fix torch2.0 dcn/mdcn symbolic

[grimoire]

Thanks for your contribution and we appreciate it a lot. The following instructions would make your pull request more healthy and more easily get feedback. If you do not understand some items, don't worry, just make the pull request and seek help from maintainers.

Motivation

Torch2.0 would parse the forward of autograd.Function, which leads to optimization failed.

Modification

1. cast dcn/mdcn shape to int so forward can also be parsed.
2. move onnxruntime inside the test. onnxruntime is optional now.

BC-breaking (Optional)

Does the modification introduce changes that break the backward-compatibility of the downstream repositories?
If so, please describe how it breaks the compatibility and how the downstream projects should modify their code to keep compatibility with this PR.

Use cases (Optional)

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

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 test to ensure the correctness.
• The documentation has been modified accordingly, including docstring or example tutorials.

After PR:

• If the modification has potential influence on downstream or other related projects, this PR should be tested with some of those projects, like MMDet or MMCls.
• CLA has been signed and all committers have signed the CLA in this PR.

[codecov]

Codecov Report

Patch coverage: 100.00% and no project coverage change.

Comparison is base (5a45fac) 65.41% compared to head (95feba1) 65.41%.

❗ Current head 95feba1 differs from pull request most recent head 6acc3e5. Consider uploading reports for the commit 6acc3e5 to get more accurate results

Additional details and impacted files

@@           Coverage Diff           @@
##              2.x    #2695   +/-   ##
=======================================
  Coverage   65.41%   65.41%           
=======================================
  Files         128      128           
  Lines        8533     8533           
  Branches     1218     1220    +2     
=======================================
  Hits         5582     5582           
  Misses       2742     2742           
  Partials      209      209           

Flag	Coverage Δ
unittests	65.41% <100.00%> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
mmcv/ops/deform_conv.py	66.66% <100.00%> (ø)
mmcv/ops/modulated_deform_conv.py	65.18% <100.00%> (ø)

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.

☔ View full report in Codecov by Sentry.
📢 Do you have feedback about the report comment? Let us know in this issue.