Migrate absl::optional to std::optional

Bug: webrtc:342905193
No-Try: True
Change-Id: Icc968be43b8830038ea9a1f5f604307220457807
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/361021
Auto-Submit: Florent Castelli <orphis@webrtc.org>
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Commit-Queue: Florent Castelli <orphis@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#42911}
diff --git a/test/fuzzers/audio_decoder_fuzzer.cc b/test/fuzzers/audio_decoder_fuzzer.cc
index 1db332e..ccfd604 100644
--- a/test/fuzzers/audio_decoder_fuzzer.cc
+++ b/test/fuzzers/audio_decoder_fuzzer.cc
@@ -11,8 +11,8 @@
 #include "test/fuzzers/audio_decoder_fuzzer.h"
 
 #include <limits>
+#include <optional>
 
-#include "absl/types/optional.h"
 #include "api/audio_codecs/audio_decoder.h"
 #include "modules/rtp_rtcp/source/byte_io.h"
 #include "rtc_base/checks.h"