Add @christopherfujino as owner of dev/ci (docker) (#48261)

diff --git a/CODEOWNERS b/CODEOWNERS
index e0bfe8a..ef5e536 100644
--- a/CODEOWNERS
+++ b/CODEOWNERS
@@ -8,5 +8,6 @@
 
 /bin/internal/goldens.version @Piinks
 /CODEOWNERS @jmagman
+/dev/ci/ @christopherfujino
 /packages/flutter_tools/templates/module/ios/ @jmagman
 /packages/flutter_tools/templates/**/Podfile* @jmagman