To be able to get access to the beta you will have to change stability flag on affected/added packages (Solr and Recommendation are optional new packages, ezfind depends if you're using it):
composer require --no-update "ezsystems/ezpublish-kernel:5.4.5-rc1 as 5.4.5"
composer require --no-update "ezsystems/ezpublish-legacy:5.4.5-rc1 as 5.4.5"
composer require --no-update "ezsystems/ezflow-ls-extension:5.3.8-rc1 as 5.3.8"
composer require --no-update "ezsystems/ezplatform-solr-search-engine:~1.0.0@rc"
composer require --no-update "ezsystems/recommendation-bundle:~1.0.0@beta"
composer require --no-update "ezsystems/ezfind-ls:5.4.5-rc1 as 5.4.5"
After this has been done follow the 5.4.x Update Instructions to apply this update to your platforms.
Every package manually updated in the root composer.json must be added the update line specified in the 5.4.x update instructions. Add
ezsystems/ezflow-ls-extension to the line. If the optional packages must be installed, add them as well:
ezsystems/ezplatform-solr-search-engine recommendation-bundle ezsystems/ezflowezfind-ls-extension recommendation-bundle to the line specified in the 5.4.x update instructions.
If they are omitted, composer will fail with a dependencies error.
After executing `composer update`, further actions are needed for Solr Search Engine Bundle, and Recommendation Bundle in order to correctly install them.