Github actions failure on PHP 7.4

[abias]

Github actions is currently failing on builds of PHP 7.4 with this Behat error:

001 Scenario: Calling the opcache management page                            # /home/runner/work/moodle-tool_opcache/moodle-tool_opcache/moodle/admin/tool/opcache/tests/behat/tool_opcache.feature:7
      And I navigate to "Server > Opcache management" in site administration # /home/runner/work/moodle-tool_opcache/moodle-tool_opcache/moodle/admin/tool/opcache/tests/behat/tool_opcache.feature:9
        Exception: Moodle exception: Exception - Notice: Undefined index: jit in [dirroot]/admin/tool/opcache/lib/opcache-gui/index.php.inc on line 499 More information about this error
        
        Exception - Notice: Undefined index: jit in [dirroot]/admin/tool/opcache/lib/opcache-gui/index.php.inc on line 499

This issue has already been reported upstream on amnuts/opcache-gui#114 and should be solved with a future release of opcache-gui