Updated card title color

Author: cwhite911

theme.scss

@@ -151,7 +151,8 @@ $dark: $gs-grey-dark-color;
 // Control the color of the active tab in a tabset
 $nav-tabs-link-active-color: $gs-secondary-alt-color;
 
-$card-title-color: $gs-secondary-alt-color;
+// Control listing card title color
+$card-title-color: $gs-grey-dark-color;
 
 // ---------------------------------------------------------------------------
 // Quarto Variables