[GHA] Re-enable backwards compatibility test! (#81795)
We should be safe to re-enable the backwards compatibility. We had previously disabled it when it failed due to @ZolotukhinM's removal of the NNC backend as these functions were no longer available.
```
is_available(Any self) -> bool available
compile(Any self, Any processed, Dict(str, Any) method_compile_spec) -> Dict(str, Any) handles
execute(Any self, Any handle, Any[] input) -> Any[] output
```
https://github.com/pytorch/pytorch/runs/7274319318?check_suite_focus=true
However, these functions were accidentally exposed and should never have been in the public schema anyway, according to a discussion with @ZolotukhinM, so we should be good to re-enable. I will run a test comparing the latest master to the commit of #81246 to ensure nothing else regressed.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/81795
Approved by: https://github.com/kit1980
