Replaced deprecated pkg_resources.packaging with packaging module (py…

…torch#113023)

Usage of `from pkg_resources import packaging` leads to a deprecation warning:
```
DeprecationWarning: pkg_resources is deprecated as an API. See https://setuptools.pypa.io/en/latest/pkg_resources.html
```
and in strict tests where warnings are errors, this leads to CI breaks, e.g.: pytorch/vision#8092

Replacing `pkg_resources.package` with `package` as it is now a pytorch dependency:
https://github.com/pytorch/pytorch/blob/fa9045a8725214c05ae4dcec5a855820b861155e/requirements.txt#L19
Pull Request resolved: pytorch#113023
Approved by: https://github.com/Skylion007

tools/dynamo/verify_dynamo.py

@@ -5,7 +5,7 @@
 import traceback
 import warnings
 
-from pkg_resources import packaging
+import packaging.version
 
 MIN_CUDA_VERSION = packaging.version.parse("11.6")
 MIN_ROCM_VERSION = packaging.version.parse("5.4")

torch/utils/cpp_extension.py

@@ -25,7 +25,7 @@
 from torch.torch_version import TorchVersion
 
 from setuptools.command.build_ext import build_ext
-from pkg_resources import packaging  # type: ignore[attr-defined]
+import packaging.version
 
 IS_WINDOWS = sys.platform == 'win32'
 IS_MACOS = sys.platform.startswith('darwin')
@@ -404,6 +404,9 @@ def _check_cuda_version(compiler_name: str, compiler_version: TorchVersion) -> N
 
     cuda_str_version = cuda_version.group(1)
     cuda_ver = packaging.version.parse(cuda_str_version)
+    if torch.version.cuda is None:
+        return
+
     torch_cuda_version = packaging.version.parse(torch.version.cuda)
     if cuda_ver != torch_cuda_version:
         # major/minor attributes are only available in setuptools>=49.4.0
@@ -2345,8 +2348,7 @@ def sanitize_flags(flags):
         # Compilation will work on earlier CUDA versions but header file
         # dependencies are not correctly computed.
         required_cuda_version = packaging.version.parse('11.0')
-        has_cuda_version = torch.version.cuda is not None
-        if has_cuda_version and packaging.version.parse(torch.version.cuda) >= required_cuda_version:
+        if torch.version.cuda is not None and packaging.version.parse(torch.version.cuda) >= required_cuda_version:
             cuda_compile_rule.append('  depfile = $out.d')
             cuda_compile_rule.append('  deps = gcc')
             # Note: non-system deps with nvcc are only supported