Add missing voice call button type

src/main/java/com/whatsapp/api/domain/templates/Button.java

@@ -13,7 +13,8 @@
 @JsonTypeInfo(use = JsonTypeInfo.Id.NAME, include = As.EXISTING_PROPERTY, property = "type")
 @JsonSubTypes({@JsonSubTypes.Type(value = PhoneNumberButton.class, name = "PHONE_NUMBER"),//
         @JsonSubTypes.Type(value = UrlButton.class, name = "URL"), //
-        @JsonSubTypes.Type(value = QuickReplyButton.class, name = "QUICK_REPLY")})
+        @JsonSubTypes.Type(value = QuickReplyButton.class, name = "QUICK_REPLY"), //
+        @JsonSubTypes.Type(value = VoiceCallButton.class, name = "VOICE_CALL")})
 public class Button {
 
     private ButtonType type;

src/main/java/com/whatsapp/api/domain/templates/VoiceCallButton.java

@@ -0,0 +1,27 @@
+package com.whatsapp.api.domain.templates;
+
+import com.fasterxml.jackson.annotation.JsonInclude;
+import com.whatsapp.api.domain.templates.type.ButtonType;
+
+/**
+ * The type Voice call button.
+ */
+@JsonInclude(JsonInclude.Include.NON_NULL)
+public class VoiceCallButton extends Button {
+
+  /**
+   * Instantiates a new Voice call button.
+   */
+  protected VoiceCallButton() {
+    super(ButtonType.VOICE_CALL);
+  }
+
+  /**
+   * Instantiates a new Quick reply button.
+   *
+   * @param text the text
+   */
+  public VoiceCallButton(String text) {
+    super(ButtonType.VOICE_CALL, text);
+  }
+}

src/main/java/com/whatsapp/api/domain/templates/type/ButtonType.java

@@ -15,5 +15,9 @@ public enum ButtonType {
     /**
      * Quick reply button type.
      */
-    QUICK_REPLY
+    QUICK_REPLY,
+    /**
+     * Voice call button type.
+     */
+    VOICE_CALL;
 }