Drop the useless PHP tokenizer extension install step (#1650)

It is bundled and enabled by default in the PHP language already, and adding this step raises a warning:
warning: tokenizer (tokenizer.so) is already loaded!

Also if this option disabled, it's still installed as part of the language anyway!

docker-compose.yml

@@ -143,7 +143,6 @@ services:
           - INSTALL_MYSQLI=${PHP_FPM_INSTALL_MYSQLI}
           - INSTALL_PGSQL=${PHP_FPM_INSTALL_PGSQL}
           - INSTALL_PG_CLIENT=${PHP_FPM_INSTALL_PG_CLIENT}
-          - INSTALL_TOKENIZER=${PHP_FPM_INSTALL_TOKENIZER}
           - INSTALL_INTL=${PHP_FPM_INSTALL_INTL}
           - INSTALL_GHOSTSCRIPT=${PHP_FPM_INSTALL_GHOSTSCRIPT}
           - INSTALL_LDAP=${PHP_FPM_INSTALL_LDAP}