Bump bootstrap-sass from 3.3.7 to 3.4.1

Bumps [bootstrap-sass](https://github.com/twbs/bootstrap-sass) from 3.3.7 to 3.4.1.
- [Release notes](https://github.com/twbs/bootstrap-sass/releases)
- [Changelog](https://github.com/twbs/bootstrap-sass/blob/master/CHANGELOG.md)
- [Commits](twbs/bootstrap-sass@v3.3.7...v3.4.1)

Signed-off-by: dependabot[bot] <[email protected]>

package.json

@@ -20,7 +20,7 @@
     "babel-polyfill": "6.26.0",
     "bip39": "2.5.0",
     "bn.js": "4.11.8",
-    "bootstrap-sass": "3.3.7",
+    "bootstrap-sass": "3.4.1",
     "classnames": "2.2.5",
     "electron-updater": "2.21.10",
     "ethereum-blockies-base64": "1.0.2",

yarn.lock

@@ -2799,10 +2799,10 @@ [email protected]:
   dependencies:
     hoek "2.x.x"
 
-bootstrap-sass@3.3.7:
-  version "3.3.7"
-  resolved "https://registry.yarnpkg.com/bootstrap-sass/-/bootstrap-sass-3.3.7.tgz#6596c7ab40f6637393323ab0bc80d064fc630498"
-  integrity sha1-ZZbHq0D2Y3OTMjqwvIDQZPxjBJg=
+bootstrap-sass@3.4.1:
+  version "3.4.1"
+  resolved "https://registry.yarnpkg.com/bootstrap-sass/-/bootstrap-sass-3.4.1.tgz#6843c73b1c258a0ac5cb2cc6f6f5285b664a8e9a"
+  integrity sha512-p5rxsK/IyEDQm2CwiHxxUi0MZZtvVFbhWmyMOt4lLkA4bujDA1TGoKT0i1FKIWiugAdP+kK8T5KMDFIKQCLYIA==
 
 boxen@^1.2.1:
   version "1.3.0"