Upgrade bootstrap

Gemfile.lock

@@ -58,14 +58,14 @@ GEM
     ast (2.4.0)
     auto_strip_attributes (2.4.0)
       activerecord (>= 4.0)
-    autoprefixer-rails (9.3.1)
+    autoprefixer-rails (9.4.9)
       execjs
     bcrypt (3.1.11)
     bindex (0.5.0)
-    bootstrap (4.1.3)
-      autoprefixer-rails (>= 6.0.3)
-      popper_js (>= 1.12.9, < 2)
-      sass (>= 3.5.2)
+    bootstrap (4.3.1)
+      autoprefixer-rails (>= 9.1.0)
+      popper_js (>= 1.14.3, < 2)
+      sassc-rails (>= 2.0.0)
     builder (3.2.3)
     byebug (10.0.1)
     capybara (2.18.0)
@@ -94,7 +94,7 @@ GEM
       warden (~> 1.2.3)
     erubi (1.7.1)
     execjs (2.7.0)
-    ffi (1.9.25)
+    ffi (1.10.0)
     formtastic (3.1.5)
       actionpack (>= 3.2.13)
     formtastic_i18n (0.6.0)
@@ -154,7 +154,7 @@ GEM
     pg (1.0.0)
     polyamorous (1.3.3)
       activerecord (>= 3.0)
-    popper_js (1.14.3)
+    popper_js (1.14.5)
     powerpack (0.1.1)
     public_suffix (3.0.2)
     puma (3.11.3)
@@ -196,8 +196,8 @@ GEM
       i18n
       polyamorous (~> 1.3.2)
     rb-fsevent (0.10.3)
-    rb-inotify (0.9.10)
-      ffi (>= 0.5.0, < 2)
+    rb-inotify (0.10.0)
+      ffi (~> 1.0)
     recaptcha (4.7.0)
       json
     responders (2.4.0)
@@ -213,7 +213,7 @@ GEM
     ruby-progressbar (1.9.0)
     ruby_dep (1.5.0)
     rubyzip (1.2.2)
-    sass (3.6.0)
+    sass (3.7.3)
       sass-listen (~> 4.0.0)
     sass-listen (4.0.0)
       rb-fsevent (~> 0.9, >= 0.9.4)
@@ -224,6 +224,15 @@ GEM
       sprockets (>= 2.8, < 4.0)
       sprockets-rails (>= 2.0, < 4.0)
       tilt (>= 1.1, < 3)
+    sassc (2.0.1)
+      ffi (~> 1.9)
+      rake
+    sassc-rails (2.1.0)
+      railties (>= 4.0.0)
+      sassc (>= 2.0)
+      sprockets (> 3.0)
+      sprockets-rails
+      tilt
     scenic (1.4.1)
       activerecord (>= 4.0.0)
       railties (>= 4.0.0)