message: style(Collapse): increase content font-size to 14px
diff: // Collapse
  @collapse-item-transition-duration: @animation-duration-base;
  -@collapse-item-content-padding: @padding-md;
  -@collapse-item-content-font-size: 13px;
  +@collapse-item-content-padding: @padding-sm @padding-md;
  +@collapse-item-content-font-size: 14px;
  @collapse-item-content-line-height: 1.5;
  @collapse-item-content-text-color: @gray-6;
  @collapse-item-content-background-color: @white;
  