Bump testem from 2.17.0 to 3.0.0

Bumps [testem](https://github.com/testem/testem) from 2.17.0 to 3.0.0.
- [Release notes](https://github.com/testem/testem/releases)
- [Commits](testem/testem@v2.17.0...v3.0.0)

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

Author: dependabot-preview[bot]

package.json

@@ -43,7 +43,7 @@
     "ora": "^3.4.0",
     "promise-map-series": "^0.2.2",
     "qunit": "^2.9.2",
-    "testem": "^2.17.0"
+    "testem": "^3.0.0"
   },
   "ember-addon": {
     "main": "index.js"

yarn.lock

@@ -2339,7 +2339,7 @@ string_decoder@~0.10.x:
 
 stringmap@~0.2.2:
   version "0.2.2"
-  resolved "http://registry.npmjs.org/stringmap/-/stringmap-0.2.2.tgz#556c137b258f942b8776f5b2ef582aa069d7d1b1"
+  resolved "https://registry.npmjs.org/stringmap/-/stringmap-0.2.2.tgz#556c137b258f942b8776f5b2ef582aa069d7d1b1"
 
 stringset@~0.2.1:
   version "0.2.1"
@@ -2402,10 +2402,10 @@ tap-parser@^7.0.0:
     js-yaml "^3.2.7"
     minipass "^2.2.0"
 
-testem@^2.17.0:
-  version "2.17.0"
-  resolved "https://registry.yarnpkg.com/testem/-/testem-2.17.0.tgz#1cb4a2a90524a088803dfe52fbf197a6fd73c883"
-  integrity sha512-PLkIlT523w5rTJPWwR4TL1EiAEa941ECV7d4pMqsB0YdnH+sCTz0loWMKCUSdhR+VijveAZ6anE/JHehE7KqMQ==
+testem@^3.0.0:
+  version "3.0.0"
+  resolved "https://registry.yarnpkg.com/testem/-/testem-3.0.0.tgz#1f1ce7003d5fa0d4e7419846c884741eec496404"
+  integrity sha512-zNLBRvGYDiF2NjwrVj3QPRDdl9JbGtjhkCdCqHglffW5kXU720IRp2udELqMo2XrlS/VzcKPbqXAXjT98j1Oow==
   dependencies:
     backbone "^1.1.2"
     bluebird "^3.4.6"