Release 2.6.4

[danielmorell]

Description of the change

This includes a few bug fixes and improvements.

Type of change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Maintenance
• New release

Code review

• This pull request has a descriptive title and information useful to a reviewer. There may be a screenshot or screencast attached
• "Ready for review" label attached to the PR and reviewers assigned
• Issue from task tracker has a link to this pull request
• Changes have been reviewed by at least one other engineer

[cyrusradfar]

lgtm!

[therealgilles]

Is there a reason this release is not visible to wpackagist?

    - Root composer.json requires wpackagist-plugin/rollbar 2.6.4, found wpackagist-plugin/rollbar[dev-trunk, 1.0.0, ..., 1.0.4, 2.0.0, ..., 2.6.3] but it does not match the constraint.

Additionally it does not seem to be fully compatible with PHP 8.1.