Remove discriminator from embed

Due to Discord deprecating discriminators, those need to be removed from the registration embed.

On Registration L156, make the following change

diff --git a/src/main/java/edu/ship/engr/discordbot/systems/Registration.java b/src/main/java/edu/ship/engr/discordbot/systems/Registration.java
--- a/src/main/java/edu/ship/engr/discordbot/systems/Registration.java
+++ b/src/main/java/edu/ship/engr/discordbot/systems/Registration.java
@@ -153,7 +153,7 @@
 
         if (requestsChannel != null) {
             EmbedBuilder builder = new EmbedBuilder();
-            builder.addField("Username", member.getUser().getName() + "#" + member.getUser().getDiscriminator(), true);
+            builder.addField("Username", member.getUser().getName(), true);
             builder.addField("Display Name", member.getAsMention(), true);
             builder.addField("Name", Util.ucfirst(name), true);