Add yet another Weather icon variant

Rain. How did we not have rain yet?

Signed-off-by: Adam Williamson <awilliam@redhat.com>

needles/gnome/apps/weather/weather_icon_smaller_rain-20230516.json

@@ -0,0 +1,15 @@
+{
+  "area": [
+    {
+      "xpos": 251,
+      "type": "match",
+      "width": 45,
+      "ypos": 253,
+      "height": 41
+    }
+  ],
+  "properties": [],
+  "tags": [
+    "weather_icon_smaller"
+  ]
+}