Add .cppm file type to cpp language configuration (helix-editor#7492)

Author: hazeycode

languages.toml

@@ -342,7 +342,7 @@ source = { git = "https://github.com/tree-sitter/tree-sitter-c", rev = "7175a6dd
 name = "cpp"
 scope = "source.cpp"
 injection-regex = "cpp"
-file-types = ["cc", "hh", "c++", "cpp", "hpp", "h", "ipp", "tpp", "cxx", "hxx", "ixx", "txx", "ino", "C", "H", "cu", "cuh"]
+file-types = ["cc", "hh", "c++", "cpp", "hpp", "h", "ipp", "tpp", "cxx", "hxx", "ixx", "txx", "ino", "C", "H", "cu", "cuh", "cppm"]
 roots = []
 comment-token = "//"
 language-servers = [ "clangd" ]