Update gallery assets version with optipng (#18327)

diff --git a/dev/benchmarks/complex_layout/pubspec.yaml b/dev/benchmarks/complex_layout/pubspec.yaml
index 68ef064..134c838 100644
--- a/dev/benchmarks/complex_layout/pubspec.yaml
+++ b/dev/benchmarks/complex_layout/pubspec.yaml
@@ -8,7 +8,7 @@
     sdk: flutter
 
   # Also examples/flutter_gallery/pubspec.yaml
-  flutter_gallery_assets: 0.1.3
+  flutter_gallery_assets: 0.1.4
 
   async: 2.0.7 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
   charcode: 1.1.1 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
@@ -75,4 +75,4 @@
     - packages/flutter_gallery_assets/people/square/ali.png
     - packages/flutter_gallery_assets/places/india_chettinad_silk_maker.png
 
-# PUBSPEC CHECKSUM: 89f2
+# PUBSPEC CHECKSUM: 77f3
diff --git a/examples/flutter_gallery/pubspec.yaml b/examples/flutter_gallery/pubspec.yaml
index e45ca02..ae2e8b7 100644
--- a/examples/flutter_gallery/pubspec.yaml
+++ b/examples/flutter_gallery/pubspec.yaml
@@ -12,7 +12,7 @@
   video_player: 0.5.1
 
   # Also update dev/benchmarks/complex_layout/pubspec.yaml
-  flutter_gallery_assets: 0.1.3
+  flutter_gallery_assets: 0.1.4
 
   charcode: 1.1.1 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
   meta: 1.1.5 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
@@ -197,4 +197,4 @@
         - asset: packages/flutter_gallery_assets/fonts/private/googlesans/GoogleSansDisplay-Regular.ttf
           weight: 400
 
-# PUBSPEC CHECKSUM: e358
+# PUBSPEC CHECKSUM: 6659