toil(guard): add anchor to calendar on signup page (#397)

## 📝 Description
As per
#91 (comment)

## ✅ Checklist
- [x] I have tested this change
- [ ] This change requires documentation update

Author: skipi

guard/templates/signup.html.eex

@@ -112,7 +112,7 @@
       </main>
     </div>
     </div>
-    <div class="calendar">
+    <div class="calendar" id="calendar">
       <div class="wrap">
         <div class="intro">
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