Add new AudienceGroupType POP_AD_IMP to Audience Group API (#1706)

line/line-openapi#113

# Add `POP_AD_IMP` to **AudienceGroupType** Enum

We have supported for the new audience‑group type **`POP_AD_IMP`**
(POP ad impression audience) to the OpenAPI schema.

## Changes Made

* **Updated `AudienceGroupType` enumeration**

  * **New value**: `POP_AD_IMP`
* **Description**: Audience groups generated from impressions of *LINE
Beacon Network* (POP) ads.
  * **Region**: **Taiwan‑only** at launch

## Purpose

This update enables correct identification and handling of audience
groups built from POP ad impressions, a feature that will be released
for the Taiwan market.

## Documents and Reference

- [Managing
Audience](https://developers.line.biz/en/reference/messaging-api/#manage-audience-group)

For more information, please refer to the links provided above.

Co-authored-by: github-actions <[email protected]>

Author: github-actions[bot]

clients/line-bot-manage-audience-client/src/main/java/com/linecorp/bot/audience/model/AudienceGroupType.java

@@ -64,6 +64,9 @@ public enum AudienceGroupType {
   @JsonProperty("RICHMENU_CLICK")
   RICHMENU_CLICK,
 
+  @JsonProperty("POP_AD_IMP")
+  POP_AD_IMP,
+
   @JsonEnumDefaultValue
   UNDEFINED;
 
@@ -82,6 +85,7 @@ public String toValue() {
       case IMAGE_CLICK -> "IMAGE_CLICK";
       case RICHMENU_IMP -> "RICHMENU_IMP";
       case RICHMENU_CLICK -> "RICHMENU_CLICK";
+      case POP_AD_IMP -> "POP_AD_IMP";
 
       default -> "UNDEFINED";
     };