Addressing warning message when using Python 3.10

When I use Python 3.10, the following line of code

https://github.com/IntelPython/dpcpp-llvm-spirv/blob/f5e58c2be288d6b65c27a80d44cb14f4ffc7e403/pkg/dpcpp_llvm_spirv/_helper.py#L16

produces the following warning message
```
SyntaxWarning: "is" with a literal. Did you mean "=="?
  if platform.system() is "Windows":
```

Could this please be addressed?

Thanks!