Adds semantic labels to images and modal close button (#56)

* Added semantic labels to images.

* Reverting project file.

* Semantic label for close button.

veggieseasons/lib/widgets/veggie_card.dart

@@ -122,6 +122,7 @@ class VeggieCard extends StatelessWidget {
           Image.asset(
             veggie.imageAssetPath,
             fit: BoxFit.cover,
+            semanticLabel: 'A card background featuring ${veggie.name}',
           ),
           Positioned(
             bottom: 0.0,