Treat patches as diff files (helix-editor#5085)

languages.toml

@@ -1083,7 +1083,7 @@ source = { git = "https://github.com/the-mikedavis/tree-sitter-git-commit", rev
 name = "diff"
 scope = "source.diff"
 roots = []
-file-types = ["diff"]
+file-types = ["diff", "patch"]
 injection-regex = "diff"
 comment-token = "#"
 indent = { tab-width = 2, unit = "  " }