Roll libpng to 134cf139cb24d802ee6ad5fc51bccff3221c2b49 (#32688)

Includes:
* Win32: Suppress tautological const compare warning

Issue: flutter/flutter#59199

Author: cbracken

DEPS

@@ -394,7 +394,7 @@ deps = {
    Var('fuchsia_git') + '/third_party/libjpeg-turbo' + '@' + '0fb821f3b2e570b2783a94ccd9a2fb1f4916ae9f',
 
   'src/third_party/libpng':
-   Var('flutter_git') + '/third_party/libpng' + '@' + '45c760458b4a83d567cc42d21bd79a3b3fe21815',
+   Var('flutter_git') + '/third_party/libpng' + '@' + '134cf139cb24d802ee6ad5fc51bccff3221c2b49',
 
   'src/third_party/libwebp':
    Var('chromium_git') + '/webm/libwebp.git' + '@' + '7dfde712a477e420968732161539011e0fd446cf', # 1.2.0