PHP 8.1 Deprecated function: Return type of IdMapFilter::accept() && Return type of Drupal\migrate_tools\SourceFilter::count()

Problem/Motivation

After upgrading to PHP 8.1, our sites got the PHP warning message said

Deprecated function: Return type of Drupal\migrate_tools\IdMapFilter::accept() should either be compatible with FilterIterator::accept(): bool, or the #[\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice in include() (line 13 of /modules/contrib/migrate_tools/src/IdMapFilter.php)

Deprecated function: Return type of Drupal\migrate_tools\SourceFilter::count() should either be compatible with Countable::count(): int, or the #[\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice in include() (line 12 of /app/web/modules/contrib/migrate_tools/src/SourceFilter.php)

Steps to reproduce

1. Upgrade PHP to 8.1.5
2. Install migrate_tools 5.1.0

Proposed resolution

Use the #[\ReturnTypeWillChange] attribute to temporarily suppress the notice.

Remaining tasks

Test scripts.

User interface changes

N/A

API changes

N/A

Data model changes

N/A