fix(parse)!: accept short constexpr function with requires

[JohelEGP]

Resolves #709.

Testing summary:

100% tests passed, 0 tests failed out of 898

Total Test time (real) =  47.56 sec

Acknowledgements:

• Tested thanks to https://github.com/modern-cmake/cppfront.
• Commit messages follow Conventional Commits 1.0.0.
• Comments and commit messages follow Semantic Line Breaks.

[hsutter]

Thanks! It's nice that that one was a simple change that could just reuse the existing angle/equality parsing opt-outs, which were created for similar situations.