roll gallery version to fix build (#79456)

diff --git a/dev/devicelab/lib/versions/gallery.dart b/dev/devicelab/lib/versions/gallery.dart
index 6c5f550..fdb540f 100644
--- a/dev/devicelab/lib/versions/gallery.dart
+++ b/dev/devicelab/lib/versions/gallery.dart
@@ -3,4 +3,4 @@
 // found in the LICENSE file.
 
 /// The pinned version of flutter gallery, used for devicelab tests.
-const String galleryVersion = 'e2cfe22e9fa0b585b719cd911439fc80a3c27f39';
+const String galleryVersion = 'bc7b2bba0bbcb54f30ffc0042120253c261aadeb';