feat(languages): Add buck2 PACKAGE files as starlark file type (#14324)

Author: tingerrr

languages.toml

@@ -2628,7 +2628,7 @@ source = { git = "https://github.com/sogaiu/tree-sitter-clojure", rev = "e57c569
 name = "starlark"
 scope = "source.starlark"
 injection-regex = "(starlark|bzl|bazel|buck)"
-file-types = ["bzl", "bazel", "star", { glob = "BUILD" }, { glob = "BUCK" }, { glob = "BUILD.*" }, { glob = "Tiltfile" }, { glob = "WORKSPACE" }, { glob = "WORKSPACE.bzlmod" }]
+file-types = ["bzl", "bazel", "star", { glob = "BUILD" }, { glob = "BUCK" }, { glob = "BUILD.*" }, { glob = "Tiltfile" }, { glob = "WORKSPACE" }, { glob = "WORKSPACE.bzlmod" }, { glob = "PACKAGE" }]
 comment-token = "#"
 indent = { tab-width = 4, unit = "    " }
 language-servers = [ "starpls" ]