Increase the max effective datarate slightly

Increase the multipler for the maximum effective datarate from 1.23 to
1.24 to make AV1/DatarateTestSpeedChangeRealtime.ChangingSpeedTest/0
pass after commit 309d0affc51a621ffafb76cf6fdc8e917c345e8e.

Bug: aomedia:3303
Change-Id: I77e26dcb805358924b727a77b3a7646ef758c879
diff --git a/test/datarate_test.cc b/test/datarate_test.cc
index af62d1e..ffa41e0 100644
--- a/test/datarate_test.cc
+++ b/test/datarate_test.cc
@@ -399,7 +399,7 @@
     ASSERT_NO_FATAL_FAILURE(RunLoop(&video));
     ASSERT_GE(effective_datarate_, cfg_.rc_target_bitrate * 0.83)
         << " The datarate for the file is lower than target by too much!";
-    ASSERT_LE(effective_datarate_, cfg_.rc_target_bitrate * 1.23)
+    ASSERT_LE(effective_datarate_, cfg_.rc_target_bitrate * 1.24)
         << " The datarate for the file is greater than target by too much!";
   }
 };