[BUILD] Exclude ninja from required packages

[phu0ngng]

Description

JAX images do not come with ninja by default; hence, one should not enforce ninja as a required package.
Enforcing ninja as a required package causes build failures when ninja is absent.
In fact, when ninja is absent, our build_ext.py could fall back to use MakeFile.

This PR removes ninja from the required package list in pyproject.toml.

Type of change

• Documentation change (change only to the documentation, either a fix or a new content)
• 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)
• Infra/Build change
• Code refactoring

Checklist:

• I have read and followed the contributing guidelines
• The functionality is complete
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

[phu0ngng]

/te-ci L0

[timmoon10]

If we go this route, we should also update the README:

TransformerEngine/README.rst

Line 162 in 1ae1d22

* **Source Build Requirements:** CMake 3.18+, Ninja, Git 2.17+, pybind11 2.6.0+

[ksivaman]

Unsure about this change, needs some thinking. Our build requirements should not be dictated by what is pre-installed in the JAX image.

[timmoon10]

I think Ninja is sufficiently useful that the build system should install it by default. If a user really wants to avoid it, they can build with --no-dependencies and the build will still work.