Remove implicit-dynamic-parameter from analysis_options.yaml (#2360)

This diagnostic is deprecated and will soon no longer be produced.
diff --git a/analysis_options.yaml b/analysis_options.yaml
index 4cf6349..cd6e90d 100644
--- a/analysis_options.yaml
+++ b/analysis_options.yaml
@@ -30,7 +30,6 @@
     missing_return: warning
     # allow having TODOs in the code
     todo: ignore
-    implicit_dynamic_parameter: info
   exclude:
     - ".dart_tool/**"
     - "**/*.g.dart"