[Fix] Individual contributor graph

When the project has only one contributor, the individual contribution graph is cropped because the container with the id 'contributors' is not taking the full width

app/assets/stylesheets/pages/stat_graph.scss

@@ -25,6 +25,8 @@
 }
 
 #contributors {
+  flex: 1;
+
   .contributors-list {
     margin: 0 0 10px;
     list-style: none;