Make downloaded binary executable in intsall script

cli/npm/install.js

@@ -51,6 +51,10 @@ get(assetURL, response => {
   response.pipe(zlib.createGunzip()).pipe(file);
 });
 
+file.on('finish', () => {
+  fs.chmodSync(executableName, '755');
+});
+
 // Follow redirects.
 function get(url, callback) {
   https.get(url, response => {

cli/npm/package-lock.json

@@ -1,5 +1,5 @@
 {
   "name": "tree-sitter-cli",
-  "version": "0.14.0-beta0",
+  "version": "0.14.0-beta1",
   "lockfileVersion": 1
 }

cli/npm/package.json

@@ -14,7 +14,7 @@
   ],
   "main": "lib/api/index.js",
   "scripts": {
-    "install": "install.js"
+    "install": "node install.js"
   },
   "bin": {
     "tree-sitter": "tree-sitter"