bot: Add missing ChatGptResponse field

This field was newly introduced an broke the serialization.
I opted against using the ignore-unknown Jackson annotation to get
informed about model changes. It might be a interesting field...
This just a hobby project :)

bot/src/main/java/de/hhhammer/dchat/bot/DiscordBot.java

@@ -38,6 +38,7 @@ public class DiscordBot implements Runnable {
                 .setToken(discordApiKey)
                 .login()
                 .join();
+        discordApi.setMessageCacheSize(10, 60*60);
         var future = new CompletableFuture<Void>();
         Runtime.getRuntime().addShutdownHook(Thread.ofVirtual().unstarted(() -> {
             logger.info("Shutting down Discord application");

bot/src/main/java/de/hhhammer/dchat/bot/openai/models/ChatGPTResponse.java

@@ -4,7 +4,13 @@ import com.fasterxml.jackson.annotation.JsonProperty;
 
 import java.util.List;
 
-public record ChatGPTResponse(String id, String object, long created, String model, Usage usage, List<Choice> choices) {
+public record ChatGPTResponse(String id,
+                              String object,
+                              long created,
+                              String model,
+                              Usage usage,
+                              List<Choice> choices,
+                              @JsonProperty("system_fingerprint") String systemFingerprint) {
 
     public record Usage(@JsonProperty("prompt_tokens") int promptTokens,
                         @JsonProperty("completion_tokens") int completionTokens,