fix(package): update semver to version 7.3.0

Closes #1136

Author: greenkeeper[bot]

package.json

@@ -34,7 +34,7 @@
     "request-promise": "^4.1.1",
     "retry-promise": "^1.0.0",
     "rollbar": "^2.0.3",
-    "semver": "^6.0.0",
+    "semver": "^7.3.0",
     "slack-notify": "^0.1.6",
     "stripe": "^6.0.0",
     "yml-in-place": "^1.0.2"