Merge branch 'fix-placeholder-color' into 'master'

Fix placeholder color
Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

See merge request !3472

app/assets/stylesheets/framework/forms.scss

@@ -91,7 +91,7 @@ label {
 }
 
 .form-control::-webkit-input-placeholder {
-  color: #7f8fa4;
+  color: $gl-placeholder-color;
 }
 
 .input-group {