Switched CupertinoDynamicColor to `implements Color` (#153938)

issue: https://github.com/flutter/flutter/issues/127855
This was an impediment to [changing the Color class](https://github.com/flutter/engine/pull/54415).
https://dart.googlesource.com/external/github.com/flutter/flutter/+/52bb0c4cee5568dfe1fd6fadcabc97f460757eb8

DEPS

diff --git a/DEPS b/DEPS
index 9551a44..b7b20e8 100644
--- a/DEPS
+++ b/DEPS
@@ -287,7 +287,7 @@
 
   'engine/src/flutter/third_party/dart': Var('dart_git') + '/sdk' + '@' + 'ad15bc4b47a02fa71d2705fd96f896950d2aa881',
 
-  'flutter': Var('flutter_git') + '/mirrors/flutter' + '@' + '76955826aeca38bd7343cadf8016adafca4aad42',
+  'flutter': Var('flutter_git') + '/mirrors/flutter' + '@' + '52bb0c4cee5568dfe1fd6fadcabc97f460757eb8',
 
   'engine/src/flutter/third_party/depot_tools':
   Var('chromium_git') + '/chromium/tools/depot_tools.git' + '@' + '580b4ff3f5cd0dcaa2eacda28cefe0f45320e8f7',

commits.json

diff --git a/commits.json b/commits.json
index 7004f8a..6e969c4 100644
--- a/commits.json
+++ b/commits.json
@@ -1,5 +1,5 @@
 {
   "engine/src/flutter":"e042202099430fe2ad95015c37fbb4582ee60bf3",
   "engine/src/flutter/third_party/dart":"ad15bc4b47a02fa71d2705fd96f896950d2aa881",
-  "flutter":"76955826aeca38bd7343cadf8016adafca4aad42"
+  "flutter":"52bb0c4cee5568dfe1fd6fadcabc97f460757eb8"
 }
\ No newline at end of file