Ensure kotlinx.datetime.LocalTime exists before adding the serializer

LocalTime was added in kotlinx.datetime v0.4.0 and won't be available
if older versions of kotlinx datetime are on the classpath.

JAVA-5641

Author: rozza

bson-kotlinx/src/main/kotlin/org/bson/codecs/kotlinx/DateTimeSerializers.kt

@@ -57,8 +57,10 @@ public val dateTimeSerializersModule: SerializersModule by lazy {
         module +=
             InstantAsBsonDateTime.serializersModule +
                 LocalDateAsBsonDateTime.serializersModule +
-                LocalDateTimeAsBsonDateTime.serializersModule +
-                LocalTimeAsBsonDateTime.serializersModule
+                LocalDateTimeAsBsonDateTime.serializersModule
+    }
+    if (isClassAvailable("kotlinx.datetime.LocalTime")) {
+        module += LocalTimeAsBsonDateTime.serializersModule
     }
     module
 }