Fix AnthropicApiIT's chatCompletionStreamError

 - Fix the error response message Signed-off-by: Ilayaperumal Gopinathan <ilayaperumal.gopinathan@broadcom.com>

Author: ilayaperumalg

models/spring-ai-anthropic/src/test/java/org/springframework/ai/anthropic/api/AnthropicApiIT.java

@@ -324,7 +324,7 @@ void chatCompletionStreamError() {
 assertThatThrownBy(() -> response.collectList().block()).isInstanceOf(RuntimeException.class)
 .hasMessageStartingWith("Response exception, Status: [")
 .hasMessageContaining(
-"{\"type\":\"error\",\"error\":{\"type\":\"authentication_error\",\"message\":\"invalid x-api-key\"}}");
+"{\"type\":\"error\",\"error\":{\"type\":\"authentication_error\",\"message\":\"invalid x-api-key\"}");
 }
 
 }