build(deps): bump intl in /auth0_flutter_platform_interface

Bumps [intl](https://github.com/dart-lang/i18n/tree/main/pkgs) from 0.18.1 to 0.20.3.
- [Release notes](https://github.com/dart-lang/i18n/releases)
- [Commits](https://github.com/dart-lang/i18n/commits/intl-v0.20.3/pkgs)

---
updated-dependencies:
- dependency-name: intl
  dependency-version: 0.20.3
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

auth0_flutter_platform_interface/pubspec.yaml

@@ -19,7 +19,7 @@ dev_dependencies:
   flutter_lints: ^2.0.1
   flutter_test:
     sdk: flutter
-  intl: ^0.18.0
+  intl: ">=0.18.0 <0.21.0"
   mockito: ^5.1.0
 
 # For information on the generic Dart part of this file, see the