Update packges (#21241)

https://github.com/flutter/flutter/issues/19578
diff --git a/examples/platform_channel/pubspec.yaml b/examples/platform_channel/pubspec.yaml
index 7ae7ab4..f97510c 100644
--- a/examples/platform_channel/pubspec.yaml
+++ b/examples/platform_channel/pubspec.yaml
@@ -27,7 +27,7 @@
   convert: 2.0.2 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
   crypto: 2.0.6 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
   csslib: 0.14.5 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
-  file: 5.0.4 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
+  file: 5.0.6 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
   front_end: 0.1.4 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
   glob: 1.1.7 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
   html: 0.13.3+3 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
@@ -72,4 +72,4 @@
 flutter:
   uses-material-design: true
 
-# PUBSPEC CHECKSUM: 0c2d
+# PUBSPEC CHECKSUM: b52f