Bump autoprefixer-rails from 10.2.5.1 to 10.4.16.0

Note we're moving the `browserlist` file to `.browserlistrc` because
that's the expected locations in new versions of autoprefixer-rails.

Bumps [autoprefixer-rails](https://github.com/ai/autoprefixer-rails) from 10.2.5.1 to 10.4.16.0.
- [Changelog](https://github.com/ai/autoprefixer-rails/blob/master/CHANGELOG.md)
- [Commits](https://github.com/ai/autoprefixer-rails/compare/10.2.5.1...10.4.16.0)

---
updated-dependencies:
- dependency-name: autoprefixer-rails
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

Gemfile.lock

@@ -87,8 +87,8 @@ GEM
     audited (5.4.3)
       activerecord (>= 5.0, < 7.2)
       request_store (~> 1.2)
-    autoprefixer-rails (10.2.5.1)
-      execjs (> 0)
+    autoprefixer-rails (10.4.16.0)
+      execjs (~> 2)
     base64 (0.1.1)
     bcrypt (3.1.20)
     better_html (2.0.2)
@@ -682,7 +682,7 @@ DEPENDENCIES
   airbrake (~> 13.0.4)
   ancestry (~> 4.3.3)
   audited (~> 5.4.3)
-  autoprefixer-rails (~> 10.2.5.1)
+  autoprefixer-rails (~> 10.4.16)
   bing_translator (~> 6.2.0)
   bullet (~> 7.1.6)
   byebug (~> 11.1.3)