Bump ember-concurrency from 1.0.0 to 2.1.2

package.json

@@ -58,7 +58,7 @@
     "ember-cli-tachyons-shim": "^4.9.1",
     "ember-cli-uglify": "^3.0.0",
     "ember-component-css": "^0.7.4",
-    "ember-concurrency": "^1.0.0",
+    "ember-concurrency": "^2.1.2",
     "ember-data": "~3.16.0",
     "ember-disable-prototype-extensions": "^1.1.3",
     "ember-export-application-global": "^2.0.0",