Roll libpng from 5140e80f1841 to 34954dfe60ef (2 revisions)

https://chromium.googlesource.com/chromium/src/third_party/libpng.git/+log/5140e80f1841..34954dfe60ef

If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/libpng-pdfium
Please CC pdfium-reviews+autoroller@googlegroups.com,thestig@chromium.org on the revert to ensure that a human
is aware of the problem.

To report a problem with the AutoRoller itself, please file a bug:
https://issues.skia.org/issues/new?component=1389291&template=1850622

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+doc/main/autoroll/README.md

Bug: None
Tbr: pdfium-reviews+autoroller@googlegroups.com
Change-Id: Idfbd2d0475f52d4c69deb95e8ec5f16fa6803164
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/118550
Bot-Commit: pdfium-autoroll <pdfium-autoroll@skia-public.iam.gserviceaccount.com>
Commit-Queue: pdfium-autoroll <pdfium-autoroll@skia-public.iam.gserviceaccount.com>
diff --git a/DEPS b/DEPS
index 0d22e40..1d7d2d2 100644
--- a/DEPS
+++ b/DEPS
@@ -143,7 +143,7 @@
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling libpng
   # and whatever else without interference from each other.
-  'libpng_revision': '5140e80f184158f316ad19ade22f15e1edb02256',
+  'libpng_revision': '34954dfe60ef2cb2c805792e1f08ff7db067a861',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling libunwind
   # and whatever else without interference from each other.