Upgrade bourbon to ^6.0.0 (#161)

yarn.lock

@@ -616,6 +616,14 @@
     "@babel/helper-regex" "^7.4.4"
     regexpu-core "^4.6.0"
 
+"@babel/polyfill@^7.6.0":
+  version "7.6.0"
+  resolved "https://registry.yarnpkg.com/@babel/polyfill/-/polyfill-7.6.0.tgz#6d89203f8b6cd323e8d946e47774ea35dc0619cc"
+  integrity sha512-q5BZJI0n/B10VaQQvln1IlDK3BTBJFbADx7tv+oXDPIDZuTo37H5Adb9jhlXm/fEN4Y7/64qD9mnrJJG7rmaTw==
+  dependencies:
+    core-js "^2.6.5"
+    regenerator-runtime "^0.13.2"
+
 "@babel/preset-env@^7.0.0 < 7.4.0":
   version "7.3.4"
   resolved "https://registry.yarnpkg.com/@babel/preset-env/-/preset-env-7.3.4.tgz#887cf38b6d23c82f19b5135298bdb160062e33e1"
@@ -2395,10 +2403,10 @@ boolbase@^1.0.0, boolbase@~1.0.0:
   resolved "https://registry.yarnpkg.com/boolbase/-/boolbase-1.0.0.tgz#68dff5fbe60c51eb37725ea9e3ed310dcc1e776e"
   integrity sha1-aN/1++YMUes3cl6p4+0xDcwed24=
 
-bourbon@~4.2.7:
-  version "4.2.7"
-  resolved "https://registry.yarnpkg.com/bourbon/-/bourbon-4.2.7.tgz#48a805dff475fbf61e002a64e1e4db68d2f82fba"
-  integrity sha1-SKgF3/R1+/YeACpk4eTbaNL4L7o=
+bourbon@^6.0.0:
+  version "6.0.0"
+  resolved "https://registry.yarnpkg.com/bourbon/-/bourbon-6.0.0.tgz#41ad318371128888261a390bebe0e9e89daaa01e"
+  integrity sha512-Skds0R1+GY3c1oBddh9BggYVq39Uo4ySvW33zttPk+4+nfGYpbZqwaDwENkbtV7PYhCk0ctTFkzfTNFv5365ag==
 
 brace-expansion@^1.1.7:
   version "1.1.11"