Update MANIFEST.in

[mhucka]

This updates the inclusion rules in MANIFEST.in.

With the current configuration, the sdist tarball ends up with basically everything, so we end up without anything to add explicitly, and instead, only have to exclude things via rules MANIFEST.in.

Note: #985 needs to be applied first.

[gemini-code-assist]

Code Review

This pull request updates MANIFEST.in to switch from an inclusion-based to an exclusion-based approach for defining the contents of the source distribution. While the new exclusion rules are beneficial for creating a clean sdist, removing the existing inclusion rules is problematic. It appears to be based on the incorrect assumption that setuptools includes all version-controlled files by default. Without a tool like setuptools-scm, this is not the case, and removing the include and graft directives will result in a broken source distribution missing essential build files. My review provides a corrected version of MANIFEST.in that combines the necessary inclusion rules with the new (and some additional) exclusion rules to ensure the package remains buildable from source.