Update Xamarin (#2297)

* Update Xamarin Hex

Xamarin hex color is officially #3498DB from branding: https://github.com/dotnet/swag/tree/master/xamarin

* Update simple-icons.json

* Update xamarin.svg

Co-authored-by: Peter Noble <PeterShaggyNoble@users.noreply.github.com>

_data/simple-icons.json

@@ -4817,8 +4817,8 @@
         },
         {
             "title": "Xamarin",
-            "hex": "4393D4",
-            "source": "https://dotnet.microsoft.com/apps/xamarin"
+            "hex": "3498DB",
+            "source": "https://github.com/dotnet/swag/tree/master/xamarin"
         },
         {
             "title": "Xbox",

icons/xamarin.svg

@@ -1 +1 @@
-<svg role="img" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><title>Xamarin icon</title><path d="M7.137 1.422c-.891 0-1.576.275-2.055 1.1-.479.821-4.389 7.61-4.8 8.226-.413.617-.413 1.374.273 2.607.686 1.234 4.115 7.269 4.527 8.024.412.755 1.028 1.2 2.055 1.2h9.73c1.03 0 1.647-.448 2.057-1.2.412-.755 3.84-6.787 4.525-8.024.681-1.233.681-1.99.272-2.607-.412-.617-4.32-7.402-4.801-8.227-.479-.821-1.164-1.1-2.055-1.1H7.137zm-.45 5.074h2.297l3.028 5.307 3.025-5.307h2.299l-3.086 5.502 3.086 5.502h-2.264l-3.06-5.307-3.06 5.307H6.687l3.083-5.502-3.084-5.502Z"/></svg>
+<svg role="img" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><title>Xamarin icon</title><path d="M6.925 1.323a1.904 1.904 0 00-1.609.93L.241 11.07a1.918 1.918 0 000 1.862l5.075 8.816c.326.56.96.929 1.609.93h10.15a1.904 1.904 0 001.609-.93l5.075-8.816a1.918 1.918 0 000-1.862l-5.075-8.816a1.904 1.904 0 00-1.609-.93zm.092 5.157a.22.22 0 01.043 0h1.75a.23.23 0 01.192.114l2.97 5.292a.228.228 0 01.028.086.228.228 0 01.028-.086l2.963-5.292a.231.231 0 01.198-.114h1.751c.155.002.271.197.199.334L14.239 12l2.9 5.179c.08.138-.04.342-.199.34h-1.75a.232.232 0 01-.2-.12l-2.962-5.292A.228.228 0 0112 12.02a.228.228 0 01-.028.086l-2.97 5.292a.231.231 0 01-.192.12H7.06c-.16.002-.278-.202-.199-.34L9.761 12l-2.9-5.186c-.07-.125.015-.307.156-.334Z"/></svg>