Add Gradle icon (#1724)

Closes #1705

_data/simple-icons.json

@@ -1255,6 +1255,11 @@
             "hex": "005EA5",
             "source": "https://github.com/alphagov/design-assets/tree/master/Icons"
         },
+        {
+            "title": "Gradle",
+            "hex": "02303A",
+            "source": "https://gradle.com/brand"
+        },
         {
             "title": "Grafana",
             "hex": "F46800",

icons/gradle.svg

@@ -0,0 +1 @@
+<svg role="img" viewBox="0 0 24 24" xmlns="http://www.w3.org/2000/svg"><title>Gradle icon</title><path d="M22.7 4.3c-1.5-1.5-3.8-1.5-5.3-.1-.1.1-.1.2-.1.3 0 .1 0 .2.1.3l.5.5c.1.1.3.1.5 0 .4-.3.8-.4 1.3-.4 1.2 0 2.2 1 2.2 2.2 0 .6-.2 1.1-.6 1.5-3 3-7.1-5.4-16.2-1.1-.6.3-.9 1-.6 1.6v.1L6 11.9c.3.6 1.1.8 1.7.5l.7-.4c.8-.5 1.5-1 2.2-1.6.1-.1.4-.1.5 0 .2.1.2.3.1.5l-.1.1c-.7.6-1.5 1.2-2.3 1.7l-.7.3c-.3.2-.6.3-1 .3-.7 0-1.4-.4-1.7-1L3.9 9.7c-2.8 2-4.6 5.9-3.6 10.8 0 .2.2.3.4.3h1.7c.2 0 .3-.1.4-.3.2-1.4 1.4-2.3 2.8-2.1 1.1.1 2 1 2.1 2.1 0 .2.2.3.4.3h1.6c.2 0 .3-.1.4-.3.2-1.4 1.4-2.3 2.8-2.1 1.1.1 2 1 2.1 2.1 0 .2.2.3.4.3H17c.2 0 .4-.2.4-.4 0-2.3.7-4.9 2.4-6.2 5.9-4.6 4.3-8.5 2.9-9.9zm-6.2 6.9l-1.2-.6c0-.4.3-.7.7-.7.4 0 .7.3.7.7.1.3 0 .5-.2.6z"/></svg>