Spring-ai Fix BedrockAnthropic3ChatModel out of bounds exception

Fix BedrockAnthropic3ChatModel handle AnthropicChatResponse out of bounds exception when response content is empty.

see: https://github.com/spring-projects/spring-ai/issues/757

Comment From: maxjiang153

re-implement with: https://github.com/spring-projects/spring-ai/pull/813

Comment From: markpollack

Fixed, please reopen if other issues are encounterd.

Comment From: maxjiang153

Will this PR be considered individually or combined with https://github.com/spring-projects/spring-ai/pull/813?

Comment From: markpollack

sorry, I thought I merged this. We very much appreciate the other PR, it is a huge help but also we need to really sit down and digest it all. So I will merge this now and #813 will be done in another step.

merged in 32a4652aba827155f94e195362b25648ff273550

thanks!