Bump rsvp from 3.6.1 to 4.8.4

Bumps [rsvp](https://github.com/tildeio/rsvp.js) from 3.6.1 to 4.8.4.
- [Release notes](https://github.com/tildeio/rsvp.js/releases)
- [Changelog](https://github.com/tildeio/rsvp.js/blob/master/CHANGELOG.md)
- [Commits](tildeio/rsvp.js@v3.6.1...v4.8.4)

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

Author: dependabot-support

package.json

@@ -31,7 +31,7 @@
     "htmlbars": "^0.14.17",
     "inflection": "^1.10.0",
     "nopt": "^4.0.1",
-    "rsvp": "^3.2.1",
+    "rsvp": "^4.8.4",
     "walk-sync": "^1.0.0"
   },
   "engines": {

yarn.lock

@@ -2579,9 +2579,9 @@ rimraf@~2.2.6:
   version "2.2.8"
   resolved "https://registry.yarnpkg.com/rimraf/-/rimraf-2.2.8.tgz#e439be2aaee327321952730f99a8929e4fc50582"
 
-rsvp@^3.2.1:
-  version "3.6.1"
-  resolved "https://registry.yarnpkg.com/rsvp/-/rsvp-3.6.1.tgz#34f4a7ac2859f7bacc8f49789c5604f1e26ae702"
+rsvp@^4.8.4:
+  version "4.8.4"
+  resolved "https://registry.yarnpkg.com/rsvp/-/rsvp-4.8.4.tgz#b50e6b34583f3dd89329a2f23a8a2be072845911"
 
 run-async@^0.1.0:
   version "0.1.0"