refactor: better SerializersModule structure

src/backend/src/main/kotlin/club/itstudio/itmanager/config/SerializationConfig.kt

@@ -1,7 +1,9 @@
 package club.itstudio.itmanager.config
 
-import club.itstudio.itmanager.utils.customSerializersModule
+import club.itstudio.itmanager.utils.BigDecimalSerializer
 import kotlinx.serialization.json.Json
+import kotlinx.serialization.modules.SerializersModule
+import kotlinx.serialization.modules.contextual
 import org.springframework.context.annotation.Bean
 import org.springframework.context.annotation.Configuration
 
@@ -10,7 +12,9 @@ class SerializationConfig {
 
     @Bean
     fun kotlinxSerializationJson(): Json = Json {
-        serializersModule = customSerializersModule
+        serializersModule = SerializersModule {
+            contextual(BigDecimalSerializer)
+        }
         ignoreUnknownKeys = true
         isLenient = true
         encodeDefaults = false

src/backend/src/main/kotlin/club/itstudio/itmanager/utils/BigDecimalSerializer.kt

@@ -9,8 +9,6 @@ import kotlinx.serialization.encoding.Decoder
 import kotlinx.serialization.encoding.Encoder
 import kotlinx.serialization.json.JsonDecoder
 import kotlinx.serialization.json.JsonPrimitive
-import kotlinx.serialization.modules.SerializersModule
-import kotlinx.serialization.modules.contextual
 import java.math.BigDecimal
 
 object BigDecimalSerializer : KSerializer<BigDecimal> {
@@ -28,8 +26,4 @@ object BigDecimalSerializer : KSerializer<BigDecimal> {
         }
         return element.content.toBigDecimal()
     }
-}
-
-val customSerializersModule = SerializersModule {
-    contextual(BigDecimalSerializer)
 }