Bootstrap version update and progressbar fix.

Yellow fee text is now white.

frontend/src/app/components/mempool-block/mempool-block.component.scss

@@ -2,12 +2,6 @@
   background-color: #2d3348;
 }
 
-.progress-text {
-  position: absolute;
-  width: 100%;
-  text-align: center;
-}
-
 .title-block {
   color: #FFF;
   padding-top: 20px;