Update drupal8 to 8.7.7

The update to 8.6.17 wasn't enough to make the annoying messages go away.

PHP 5 support, automatic entity updates, and Internet Explorer 9 workarounds
have been removed

     * PHP 5.5 and 5.6 will no longer be supported as of Drupal 8.7.0.
       As of December 2018, PHP 5.6 no longer receives security support
       from the maintainers of PHP. Anyone running Drupal 8 on PHP 5.5 or
       5.6 should upgrade their PHP version to at least 7.1. PHP 7.2 is
       now recommended. Read more in the change record for the PHP
       requirement update.
     * Starting with 8.7.0, Drupal core no longer provides support for
       automatic entity updates as these have resulted in conflicts with
       regular database updates and data integrity issues. Whenever an
       entity type or field storage definition needs to be created,
       changed or deleted, it has to be done with an explicit update
       function as provided by the Update API, and using the API provided
       by the entity definition update manager. (Note that using the API
       has always been the recommended way for developers to trigger
       entity updates.) drush entup is also no longer supported by Drupal
       core. These three change records provide further details:
         1. Support for automatic entity updates has been removed
         2. Kernel tests have to install entity type schemas for all the
            entity types they are testing, and before installing any other
            configuration
         3. New helper method available to set up the "current_user"
            service in kernel tests
     * Workarounds for the stylesheet limit in Internet Explorer 9 (IE9)
       and earlier have been removed. Drupal dropped support for Internet
       Explorer 9 and 10 in 8.4.0, but Drupal 8.5 and 8.6 retained a
       workaround to allow 32 or more stylesheets to be included. This
       workaround has been removed in 8.7. Sites still requiring Internet
       Explorer 9 support for the work around of IE's limit of 31 style
       sheets per page, should enable CSS aggregation (preferred) or
       install the IE9 Compatibility contributed module.

Extensive release notes here:
- https://www.drupal.org/project/drupal/releases/8.7.0
- https://www.drupal.org/project/drupal/releases/8.7.7


(prlw1)