use proper symbol for Celsius and Fahrenheit

small correction

site/content/examples/20-7guis/02-7guis-temperature/App.svelte

@@ -14,11 +14,11 @@
 </script>
 
 <!-- https://eugenkiss.github.io/7guis/tasks/#temp -->
-<input value={c} on:input="{e => setBothFromC(e.target.value)}" type=number> °c =
+<input value={c} on:input="{e => setBothFromC(e.target.value)}" type=number> °C =
-<input value={f} on:input="{e => setBothFromF(e.target.value)}" type=number> °f
+<input value={f} on:input="{e => setBothFromF(e.target.value)}" type=number> °F
 
 <style>
 	input {
 		width: 5em;
 	}
-</style>
+</style>