when I start to develop my project the last version of firebase was 8 now there is a new version 9 with a big change. now they use js module and the firebase documentation advice to change to the new version. the project is big and to change I almost need to rewrite everything. do I complete my project with Firebase 8? and I want to know if there is chance for firebase to remove the support from version 8 or remove it all and only version 9 will work.