Fix OpenAiChatModelIT#streamingWithTokenUsage

 - Modify the streaming vs call usage assertion to match the close to 25% value
   - This change is done because the OpenAI chat response for call and stream invocation results in slight change in usage.

Author: ilayaperumalg

models/spring-ai-openai/src/test/java/org/springframework/ai/openai/chat/OpenAiChatModelIT.java

@@ -27,6 +27,7 @@
 import java.util.stream.Collectors;
 import java.util.stream.IntStream;
 
+import org.assertj.core.data.Percentage;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.condition.EnabledIfEnvironmentVariable;
 import org.junit.jupiter.params.ParameterizedTest;
@@ -216,9 +217,9 @@ void streamingWithTokenUsage() {
 		assertThat(streamingTokenUsage.getGenerationTokens()).isGreaterThan(0);
 		assertThat(streamingTokenUsage.getTotalTokens()).isGreaterThan(0);
 
-		assertThat(streamingTokenUsage.getPromptTokens()).isEqualTo(referenceTokenUsage.getPromptTokens());
-		assertThat(streamingTokenUsage.getGenerationTokens()).isEqualTo(referenceTokenUsage.getGenerationTokens());
-		assertThat(streamingTokenUsage.getTotalTokens()).isEqualTo(referenceTokenUsage.getTotalTokens());
+		assertThat(streamingTokenUsage.getPromptTokens()).isCloseTo(referenceTokenUsage.getPromptTokens(), Percentage.withPercentage(25));
+		assertThat(streamingTokenUsage.getGenerationTokens()).isCloseTo(referenceTokenUsage.getGenerationTokens(), Percentage.withPercentage(25));
+		assertThat(streamingTokenUsage.getTotalTokens()).isCloseTo(referenceTokenUsage.getTotalTokens(), Percentage.withPercentage(25));
 
 	}