Build for LLVM 18

[h-vetinari]

There's a new upstream version again, but we just merged #63, and more importantly, it wants to compile in C++20 mode; for that, I'd like to use newer compilers than clang 15 TBH (which is waiting for the stdlib enablement).

no need to bump the build number

[conda-forge-webservices]

Hi! This is the friendly automated conda-forge-linting service.

I just wanted to let you know that I linted all conda-recipes in your PR (recipe) and found it was in an excellent condition.

I do have some suggestions for making it better though...

For recipe:

•         'Test On Native Only' is deprecated.
  

This was used for disabling testing for cross-compiling.

This has been deprecated in favor of the top-level `test` field.
It is now mapped to `test: native_and_emulated`.

        Failed validating 'deprecated' in schema['properties']['test_on_native_only']:
            {'anyOf': [{'type': 'boolean'}, {'type': 'null'}],
             'default': False,
             'deprecated': True,
             'description': 'This was used for disabling testing for '
                            'cross-compiling.\n'
                            '\n'
                            '```warning\n'
                            'This has been deprecated in favor of the top-level '
                            '`test` field.\n'
                            'It is now mapped to `test: native_and_emulated`.\n'
                            '```',
             'title': 'Test On Native Only'}

        On instance['test_on_native_only']:
            True

[conda-forge-webservices]

Hi! This is the friendly automated conda-forge-linting service.

I just wanted to let you know that I linted all conda-recipes in your PR (recipe) and found it was in an excellent condition.