fix: remove property deprecated for flutter version 3.32.x

[cassianolucas]

This PR fixes a build error when compiling for Flutter 3.32.6 or newer.
The SearchInputDecoration class was incorrectly using super.visualDensity, which is no longer supported in the constructor of InputDecoration in recent versions of Flutter.
This caused web builds (e.g. using flutter build web) to fail with the following error:

Error: The super constructor has no corresponding named parameter.
    super.visualDensity,

Fixes: Build failure when using Flutter 3.32.6+

Pre-launch Checklist

• I read the Contributor Guide and followed the process outlined there for submitting PRs.
• I listed at least one issue that this PR fixes in the description above.
• I updated/added relevant documentation (doc comments with ///).
• I added new tests to check the change I am making, or this PR is [test-exempt].
• All existing and new tests are passing using flutter test