Plugins don't work on PHP 8

[gregrickaby]

Discussed in #956

^{Originally posted by rem7i March 2, 2022}
All six WDS Headless plugins are NOT working on PHP 8+
You can install them, but CANNOT activate at all.
Are you working to fix this or we MUST downgrade the PHP Version?

[emilse-webdev]

Fatal error: Uncaught TypeError: call_user_func_array(): Argument #1 ($function) must be a valid callback, function "WDS_Headless_SEO\activation_callback" not found or invalid function name in wp-includes\class-wp-hook.php on line 307
WDS Headless (Algolia)
WDS Headless (Blocks)
WDS Headless (Core)
WDS Headless (Gravity Forms)
WDS Headless (SEO)
same error with this five plugins.

[markus2610]

In wds-headless-core.php require 'vendor/autoload.php'
In compose:
"autoload": { "files": [ "activation.php", "deactivation.php" ] }
composer update