Fixing v3 issues

[szepeviktor]

Please consider running static analysis.
You will benefit from it. It will find bugs.

phpstan.neon.dist

includes:
    - vendor/szepeviktor/phpstan-wordpress/extension.neon
parameters:
    level: 5
    inferPrivatePropertyTypeFromConstructor: true
    scanFiles:
        - vendor/php-stubs/acf-pro-stubs/acf-pro-stubs.php
    paths:
        - oowp.php
        - src/
    ignoreErrors:
        # Uses func_get_args()
        - '#^Function apply_filters(_ref_array)? invoked with [34567] parameters, 2 required\.$#'

[szepeviktor]

Maybe composer require --dev scribu/lib-posts-to-posts:dev-master scribu/scb-framework:dev-master
and

    scanDirectories:
        - vendor/scribu/lib-posts-to-posts/