Extend WebRTC-Audio-OpusGeneratePlc

It's currently only used for testing but the initially selected end date
proved to be too short.

Bug: webrtc:13322
Change-Id: I459f315f2bad4592a1ab13190eca88a7d7cd7f90
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/345703
Commit-Queue: Emil Lundmark <lndmrk@webrtc.org>
Reviewed-by: Jakob Ivarsson‎ <jakobi@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#42031}
diff --git a/experiments/field_trials.py b/experiments/field_trials.py
index 71a9ed3..a174367 100755
--- a/experiments/field_trials.py
+++ b/experiments/field_trials.py
@@ -49,7 +49,7 @@
                date(2024, 4, 1)),
     FieldTrial('WebRTC-Audio-OpusGeneratePlc',
                'webrtc:13322',
-               date(2024, 4, 1)),
+               date(2025, 4, 1)),
     FieldTrial('WebRTC-Audio-PriorityBitrate',
                'webrtc:15769',
                date(2024, 4, 1)),