Replace fa-exclamation-triangle in MR listing page

With `warning-solid` from GitLab SVG

app/views/projects/merge_requests/_merge_request.html.haml

@@ -51,7 +51,7 @@
         - if merge_request.open? && merge_request.broken?
           %li.issuable-pipeline-broken.d-none.d-sm-flex
             = link_to merge_request_path(merge_request), class: "has-tooltip", title: _('Cannot be merged automatically') do
-              = icon('exclamation-triangle')
+              = sprite_icon('warning-solid', size: 16)
         - if merge_request.assignees.any?
           %li.d-flex
             = render 'shared/issuable/assignees', project: merge_request.project, issuable: merge_request