chore: update dependency flutter to v2.1.0 (#118)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

.circleci/config.yml

@@ -1,7 +1,7 @@
 version: 2.1
 
 orbs:
-  flutter: circleci/flutter@2.0.4
+  flutter: circleci/flutter@2.1.0
   node: circleci/[email protected]
 
 executors: