raise username length cap

app/templates/users/sign_up.html

@@ -13,7 +13,7 @@ Please read the rules etc. stub
 {%- endif -%}
 <form class="plank primary-bg full-width" method="POST">
   <label for="username">Username</label>
-  <input type="text" id="username" name="username" pattern="[a-zA-Z0-9_\-]{3,20}" title="3-20 characters. Only upper and lowercase letters, digits, hyphens, and underscores" autocomplete="username" required>
+  <input type="text" id="username" name="username" pattern="[a-zA-Z0-9_\-]{3,24}" title="3-24 characters. Only upper and lowercase letters, digits, hyphens, and underscores" autocomplete="username" required>
   <label for="password">Create password</label>
   <input type="password" id="password" name="password" pattern="(?=.*[a-z])(?=.*[A-Z])(?=.*\d)(?=.*[\W_])(?!.*\s).{10,255}" title="10+ chars with: 1 uppercase, 1 lowercase, 1 number, 1 special char, and no spaces" autocomplete="new-password" required>
   <label for="password2">Confirm password</label>