Bump bootstrap-sass from 3.3.7 to 3.4.0

Bumps [bootstrap-sass](https://github.com/twbs/bootstrap-sass) from 3.3.7 to 3.4.0.
- [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...v3.4.0)

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

Author: dependabot-support

Gemfile.lock

@@ -54,7 +54,7 @@ GEM
       io-like (~> 0.3.0)
     arel (9.0.0)
     ast (2.4.0)
-    autoprefixer-rails (9.2.1)
+    autoprefixer-rails (9.4.3)
       execjs
     awesome_print (1.8.0)
     babel-source (5.8.35)
@@ -69,9 +69,9 @@ GEM
     bindex (0.5.0)
     binding_of_caller (0.8.0)
       debug_inspector (>= 0.0.1)
-    bootstrap-sass (3.3.7)
+    bootstrap-sass (3.4.0)
       autoprefixer-rails (>= 5.2.1)
-      sass (>= 3.3.4)
+      sassc (>= 2.0.0)
     bugsnag (6.10.0)
       concurrent-ruby (~> 1.0)
     builder (3.2.3)
@@ -313,8 +313,8 @@ GEM
     rainbow (3.0.0)
     rake (12.3.1)
     rb-fsevent (0.10.3)
-    rb-inotify (0.9.10)
-      ffi (>= 0.5.0, < 2)
+    rb-inotify (0.10.0)
+      ffi (~> 1.0)
     react-rails (2.4.7)
       babel-transpiler (>= 0.7.0)
       connection_pool
@@ -360,7 +360,7 @@ GEM
     ruby_dep (1.5.0)
     rubyzip (1.2.2)
     safe_yaml (1.0.4)
-    sass (3.6.0)
+    sass (3.7.2)
       sass-listen (~> 4.0.0)
     sass-listen (4.0.0)
       rb-fsevent (~> 0.9, >= 0.9.4)
@@ -371,6 +371,9 @@ GEM
       sprockets (>= 2.8, < 4.0)
       sprockets-rails (>= 2.0, < 4.0)
       tilt (>= 1.1, < 3)
+    sassc (2.0.0)
+      ffi (~> 1.9.6)
+      rake
     selenium-webdriver (3.141.0)
       childprocess (~> 0.5)
       rubyzip (~> 1.2, >= 1.2.2)