update regex to look for "discordapp"

src/Discord.Net.Webhook/DiscordWebhookClient.cs

@@ -32,7 +32,7 @@ namespace Discord.Webhook
             : this(webhookUrl, new DiscordRestConfig()) { }
 
         // regex pattern to match webhook urls
-        private static Regex WebhookUrlRegex = new Regex(@"^.+.com\/api\/webhooks\/([\d]+)\/([a-z0-9_-]+)$", RegexOptions.Compiled | RegexOptions.IgnoreCase);
+        private static Regex WebhookUrlRegex = new Regex(@"^.*discordapp\.com\/api\/webhooks\/([\d]+)\/([a-z0-9_-]+)$", RegexOptions.Compiled | RegexOptions.IgnoreCase);
 
         /// <summary> Creates a new Webhook Discord client. </summary>
         public DiscordWebhookClient(ulong webhookId, string webhookToken, DiscordRestConfig config)

test/Discord.Net.Tests/Tests.DiscordWebhookClient.cs

@@ -19,7 +19,7 @@ namespace Discord
         // don't care about https
         [InlineData("http://canary.discordapp.com/api/webhooks/123412347732897802/_abcde123456789-ABCDEFGHIJKLMNOP12345678-abcdefghijklmnopABCDEFGHIJK")]
         // this is the minimum that the regex cares about
-        [InlineData("p.com/api/webhooks/123412347732897802/_abcde123456789-ABCDEFGHIJKLMNOP12345678-abcdefghijklmnopABCDEFGHIJK")]
+        [InlineData("discordapp.com/api/webhooks/123412347732897802/_abcde123456789-ABCDEFGHIJKLMNOP12345678-abcdefghijklmnopABCDEFGHIJK")]
         public void TestWebhook_Valid(string webhookurl)
         {
             try