Drupal 9 ready

See reports generated by upgrade_status:

CONTRIBUTED PROJECTS
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Commerce Reporting
Scanned on Jul 15, 2021.

3 warnings found.

web/modules/contrib/commerce_reports/src/EventSubscriber/OrderPlacedEventSubscri
ber.php:
┌──────────┬──────┬──────────────────────────────────────────────────────────────┐
│  STATUS  │ LINE │                           MESSAGE                            │
├──────────┼──────┼──────────────────────────────────────────────────────────────┤
│ Check    │ 73   │ Parameter $event of method                                   │
│ manually │      │ Drupal\commerce_reports\EventSubscriber\OrderPlacedEventSubs │
│          │      │ criber::generateReports() has typehint with deprecated class │
│          │      │ Symfony\Component\HttpKernel\Event\PostResponseEvent: since  │
│          │      │ Symfony 4.3, use TerminateEvent instead                      │
│          │      │                                                              │
└──────────┴──────┴──────────────────────────────────────────────────────────────┘

web/modules/contrib/commerce_reports/tests/src/Kernel/OrderReportGenerationTest.
php:
┌──────────┬──────┬─────────────────────────────────────────────────────────────┐
│  STATUS  │ LINE │                           MESSAGE                           │
├──────────┼──────┼─────────────────────────────────────────────────────────────┤
│ Check    │ 110  │ Instantiation of deprecated class                           │
│ manually │      │ Symfony\Component\HttpKernel\Event\PostResponseEvent: since │
│          │      │ Symfony 4.3, use TerminateEvent instead                     │
│          │      │                                                             │
└──────────┴──────┴─────────────────────────────────────────────────────────────┘

web/modules/contrib/commerce_reports/commerce_reports.info.yml:
┌──────────┬──────┬────────────────────────────────────────────────────────────┐
│  STATUS  │ LINE │                          MESSAGE                           │
├──────────┼──────┼────────────────────────────────────────────────────────────┤
│ Check    │ 0    │ Value of core_version_requirement: ^8.8 || ^9 is not       │
│ manually │      │ compatible with the next major version of Drupal core. See │
│          │      │ https://drupal.org/node/3070687.                           │
│          │      │                                                            │
└──────────┴──────┴────────────────────────────────────────────────────────────┘

Also, EntityManager is deprecated, which is replaced by EntityTypeManager