Adjust animations lint rules (#814)

animations/analysis_options.yaml

@@ -12,10 +12,10 @@ linter:
     cancel_subscriptions: true
     close_sinks: true
     directives_ordering: true
+    # Required because of the numbered sources in  lib/src/basics
     file_names: false
     package_api_docs: true
     package_prefixed_library_names: true
     test_types_in_equals: true
     throw_in_finally: true
     unnecessary_statements: true
-    use_key_in_widget_constructors: false