Auto-update homebrew formula on release (#122)

Co-authored-by: Natalie Weizenbaum <nweiz@google.com>

.github/workflows/ci.yml

@@ -302,6 +302,22 @@ jobs:
         run: dart run grinder pkg-github-${{ matrix.platform }}
         env: {GH_BEARER_TOKEN: "${{ github.token }}"}
 
+  deploy_homebrew:
+    name: "Deploy Homebrew"
+    runs-on: ubuntu-latest
+    needs: [dart_tests, sass_spec, static_analysis, format]
+    if: "startsWith(github.ref, 'refs/tags/') && github.repository == 'sass/dart-sass-embedded'"
+
+    steps:
+      - uses: actions/checkout@v2
+      - uses: dart-lang/setup-dart@v1
+      - run: dart pub get
+      - name: Deploy
+        run: dart pub run grinder pkg-homebrew-update
+        env:
+          GH_TOKEN: "${{ secrets.GH_TOKEN }}"
+          GH_USER: sassbot
+
   release_embedded_host:
     name: "Release Embedded Host"
     runs-on: ubuntu-latest

tool/grind.dart

@@ -11,7 +11,15 @@ import 'package:yaml/yaml.dart';
 import 'utils.dart';
 
 void main(List<String> args) {
+  pkg.humanName.value = "Dart Sass Embedded";
+  pkg.botName.value = "Sass Bot";
+  pkg.botEmail.value = "sass.bot.beep.boop@gmail.com";
+  pkg.homebrewRepo.value = "sass/homebrew-sass";
+  pkg.homebrewFormula.value = "dart-sass-embedded.rb";
+
   pkg.githubBearerToken.fn = () => Platform.environment["GH_BEARER_TOKEN"]!;
+  pkg.githubUser.fn = () => Platform.environment["GH_USER"];
+  pkg.githubPassword.fn = () => Platform.environment["GH_TOKEN"];
 
   pkg.environmentConstants.fn = () => {
         ...pkg.environmentConstants.defaultValue,
@@ -22,6 +30,7 @@ void main(List<String> args) {
       };
 
   pkg.addGithubTasks();
+  pkg.addHomebrewTasks();
   grind(args);
 }