Fixed device part image URI to be relative

Accidentally was using the full URL but this needs to be relative in order to serve content on different devices (i.e. desktop, mobile, etc).

Milestone: patch

app/views/parts/device.rb

@@ -46,7 +46,7 @@ module Terminus
         def image_uri
           fetcher.call(
             Pathname(settings.images_root).join("generated"),
-            images_uri: "https://localhost:2443/assets/images"
+            images_uri: "/assets/images"
           )[:image_url]
         end
       end

spec/app/views/parts/device_spec.rb

@@ -28,7 +28,7 @@ RSpec.describe Terminus::Views::Parts::Device, :db do
     end
 
     it "answers URI" do
-      expect(part.image_uri).to eq("https://localhost:2443/assets/images/generated/test.bmp")
+      expect(part.image_uri).to eq("/assets/images/generated/test.bmp")
     end
   end