hack the web dependency to satisfy pana downgrade deps analyzer

dart/pubspec.yaml

@@ -34,3 +34,17 @@ dev_dependencies:
   collection: ^1.16.0
   coverage: ^1.3.0
   intl: '>=0.17.0 <1.0.0'
+
+# We don't want to add web as a dependency, because it would break compatibility with old Flutter versions.
+# This is a workaround for PANA downgrade dependency analyzer issue:
+# 0/20 points: Compatible with dependency constraint lower bounds
+# downgrade analysis failed failed with 4 errors:
+#
+# URI_DOES_NOT_EXIST - lib/src/event_processor/enricher/web_enricher_event_processor.dart:3:8 - Target of URI doesn't exist: 'package:web/web.dart'.
+# URI_DOES_NOT_EXIST - lib/src/origin_web.dart:3:8 - Target of URI doesn't exist: 'package:web/web.dart'.
+# UNDEFINED_IDENTIFIER - lib/src/origin_web.dart:6:30 - Undefined name 'window'.
+# Run dart pub downgrade and then dart analyze to reproduce the above problem.
+#
+# You may run dart pub upgrade --tighten to update your dependency constraints, see dart.dev/go/downgrade-testing for details.
+dependency_overrides:
+  web: ^0.5.1