Bump mini_racer from 0.6.3 to 0.6.4

Bumps [mini_racer](https://github.com/discourse/mini_racer) from 0.6.3 to 0.6.4.
- [Changelog](https://github.com/rubyjs/mini_racer/blob/main/CHANGELOG)
- [Commits](rubyjs/mini_racer@v0.6.3...v0.6.4)

---
updated-dependencies:
- dependency-name: mini_racer
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Gemfile.lock

@@ -148,9 +148,9 @@ GEM
       rails-dom-testing (>= 1, < 3)
       railties (>= 4.2.0)
       thor (>= 0.14, < 2.0)
-    libv8-node (16.10.0.0)
-    libv8-node (16.10.0.0-x86_64-darwin-19)
-    libv8-node (16.10.0.0-x86_64-linux)
+    libv8-node (16.19.0.1)
+    libv8-node (16.19.0.1-x86_64-darwin)
+    libv8-node (16.19.0.1-x86_64-linux)
     llhttp-ffi (0.4.0)
       ffi-compiler (~> 1.0)
       rake (~> 13.0)
@@ -167,8 +167,8 @@ GEM
     method_source (1.0.0)
     mini_mime (1.1.2)
     mini_portile2 (2.8.1)
-    mini_racer (0.6.3)
-      libv8-node (~> 16.10.0.0)
+    mini_racer (0.6.4)
+      libv8-node (~> 16.19.0.0)
     minitest (5.17.0)
     multi_json (1.15.0)
     multipart-post (2.2.3)