Use common string for items unit in Bring (#131834)

homeassistant/components/bring/strings.json

 {
+  "common": {
+    "shopping_list_items": "items"
+  },
   "config": {
     "step": {
       "user": {
@@ -30,15 +33,15 @@
     "sensor": {
       "urgent": {
         "name": "Urgent",
-        "unit_of_measurement": "items"
+        "unit_of_measurement": "[%key:component::bring::common::shopping_list_items%]"
       },
       "convenient": {
         "name": "On occasion",
-        "unit_of_measurement": "items"
+        "unit_of_measurement": "[%key:component::bring::common::shopping_list_items%]"
       },
       "discounted": {
         "name": "Discount only",
-        "unit_of_measurement": "items"
+        "unit_of_measurement": "[%key:component::bring::common::shopping_list_items%]"
       },
       "list_language": {
         "name": "Region & language",