fix(device_info_plus): fix type casting for WASM

[GiacomoPignoni]

Description

Fix some types casting on web implementation for WASM compilation

Related Issues

• FIX #2966

Checklist

• [x] I read the Contributor Guide and followed the process outlined there for submitting PRs.
• [x] I titled the PR using Conventional Commits.
• [x] I did not modify the CHANGELOG.md nor the plugin version in pubspec.yaml files.
• [x] All existing and new tests are passing.
• [x] The analyzer (flutter analyze) does not report any problems on my PR.