Roll libpng from cf7c36ed084c to 28213bcabe21 (1 revision)

https://chromium.googlesource.com/chromium/src/third_party/libpng.git/+log/cf7c36ed084c..28213bcabe21

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 andyphan@google.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: andyphan@google.com
Change-Id: I58a8b164e4f337a71c6379aa508b6a8ec6703776
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/128030
Commit-Queue: pdfium-autoroll <pdfium-autoroll@skia-public.iam.gserviceaccount.com>
Bot-Commit: pdfium-autoroll <pdfium-autoroll@skia-public.iam.gserviceaccount.com>
diff --git a/DEPS b/DEPS
index b30b3b2..15bd58f 100644
--- a/DEPS
+++ b/DEPS
@@ -164,7 +164,7 @@
   # 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': 'cf7c36ed084cd051100c4a1597a901c08377b835',
+  'libpng_revision': '28213bcabe2117da81588720575e5599bafa18da',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling libunwind
   # and whatever else without interference from each other.