fix public headers in Package.swift

[charles-zablit]

This fixes an issue in Package.swift which causes the Swift compiler to complain about an umbrella already defined.

[ObserverOfTime]

I assume that would strip the TreeSitter* directory (which may or may not be needed).

Can you post the command you ran and the warning/error you're getting?

[charles-zablit]

I ran the command through Xcode by running a build.

The error looks like this:

/Users/charleszablit/Library/Developer/Xcode/DerivedData/xml-linter-bhaqsafzznnnhofiuszenyvekpfi/Build/Intermediates.noindex/InstallIntermediates/macosx/Intermediates.noindex/GeneratedModuleMaps/TreeSitterXML.modulemap:2:1: error: umbrella for module 'TreeSitterDTD' already covers this directory
umbrella "/Users/charleszablit/Developer/tree-sitter-xml/bindings/swift"
^
/Users/charleszablit/Library/Developer/Xcode/DerivedData/xml-linter-bhaqsafzznnnhofiuszenyvekpfi/Build/Intermediates.noindex/InstallIntermediates/macosx/Intermediates.noindex/GeneratedModuleMaps/TreeSitterXML.modulemap:2:1: error: umbrella for module 'TreeSitterDTD' already covers this directory
umbrella "/Users/charleszablit/Developer/tree-sitter-xml/bindings/swift"
^
<unknown>:0: error: could not build Objective-C module 'SwiftShims'

The changes in this PR fix the issue and builds and runs correctly 👍

[ObserverOfTime]

The changes in this PR fix the issue and builds and runs correctly

But now you will have xml.h instead of TreeSitterXML/xml.h if it gets installed anywhere.

That change needs to be submitted upstream first and reviewed by other Swift users. https://github.com/tree-sitter/tree-sitter/blob/master/cli/src/generate/grammar_files.rs#L441