feat(gson): 添加 Gson 适配器以支持 Java 8 日期时间 API

- 新增 `LocalDateTimeTypeAdapter`、`LocalDateTypeAdapter` 和 `ZonedDateTimeTypeAdapter`
- 将 Gson 作为可选依赖

plusone-commons/pom.xml

@@ -55,6 +55,13 @@
             <optional>true</optional>
         </dependency>
 
+        <!-- Gson -->
+        <dependency>
+            <groupId>com.google.code.gson</groupId>
+            <artifactId>gson</artifactId>
+            <optional>true</optional>
+        </dependency>
+
         <!-- ========== Test Dependencies ========== -->
 
         <dependency>
@@ -111,12 +118,6 @@
             <artifactId>jackson-datatype-jsr310</artifactId>
             <scope>test</scope>
         </dependency>
-        <!-- Gson -->
-        <dependency>
-            <groupId>com.google.code.gson</groupId>
-            <artifactId>gson</artifactId>
-            <scope>test</scope>
-        </dependency>
 
     </dependencies>