Uses tree-sitter 0.20.9 (#337)

Package.resolved

@@ -3,11 +3,11 @@
     "pins": [
       {
         "package": "TreeSitter",
-        "repositoryURL": "https://github.com/simonbs/tree-sitter",
+        "repositoryURL": "git@github.com:tree-sitter/tree-sitter.git",
         "state": {
           "branch": null,
-          "revision": "8456f7eb7a70addb3c0af8a757f1997ae9af3ed6",
-          "version": "0.20.9-beta-2"
+          "revision": "98be227227af10cc7a269cb3ffb23686c0610b17",
+          "version": "0.20.9"
         }
       }
     ]

Package.swift

@@ -13,9 +13,7 @@ let package = Package(
         .library(name: "Runestone", targets: ["Runestone"])
     ],
     dependencies: [
-        // Tree-sitter supports SPM but as of writing this, the official Tree-sitter repository has no versions published that contains the Package.swift file. Therefore, we depend on a fork of Tree-sitter that has a version published.
-        // We will pin against the official version of Tree-sitter as soon as a new version is published.
-        .package(url: "https://github.com/simonbs/tree-sitter", from: "0.20.9-beta-2")
+        .package(url: "[email protected]:tree-sitter/tree-sitter.git", from: "0.20.9")
     ],
     targets: [
         .target(name: "Runestone", dependencies: [