Stop building 32-bit packages for macOS

32-bit Dart SDKs for macOS no longer exist, so the deploy script
attempting to download them was causing the entire GitHub release to
fail.

Author: jathak

pubspec.lock

@@ -86,7 +86,7 @@ packages:
     source: hosted
     version: "0.13.9"
   crypto:
-    dependency: transitive
+    dependency: "direct dev"
     description:
       name: crypto
       url: "https://pub.dartlang.org"
@@ -149,7 +149,7 @@ packages:
     source: hosted
     version: "0.3.4"
   js:
-    dependency: "direct dev"
+    dependency: "direct main"
     description:
       name: js
       url: "https://pub.dartlang.org"

tool/grind/standalone.dart

@@ -51,7 +51,7 @@ package() async {
   var client = http.Client();
   await Future.wait(["linux", "macos", "windows"].expand((os) => [
         _buildPackage(client, os, x64: true),
-        _buildPackage(client, os, x64: false)
+        if (os != "macos") _buildPackage(client, os, x64: false)
       ]));
   client.close();
 }