Remove linter rules removed in Dart 3.3.0

[FrankenApps]

On my machine using Dart 3.11, I get the following analyzer warning about removed rules:

user@machine flutter_zxing > dart analyze
Analyzing flutter_zxing...             4.2s

warning • analysis_options.yaml:40:7 • 'always_require_non_null_named_parameters' was removed in Dart '3.3.0' Try removing the reference to
          'always_require_non_null_named_parameters'. • removed_lint
warning • analysis_options.yaml:70:7 • 'avoid_returning_null_for_future' was removed in Dart '3.3.0' Try removing the reference to
          'avoid_returning_null_for_future'. • removed_lint
warning • analysis_options.yaml:148:7 • 'prefer_equal_for_default_values' was removed in Dart '3.0.0' Try removing the reference to
          'prefer_equal_for_default_values'. • removed_lint

I removed these rules and now dart analyze completes without any warnings.