Add an upgrade note about the removal of Serializable
Add an upgrade note about the removal of Serializable

paradajozsef/symfony,Tobion/symfony,symfony/symfony,oleg-andreyev/symfony,stof/symfony,HeahDude/symfony,derrabus/symfony,ro0NL/symfony,oleg-andreyev/symfony,xabbuh/symfony,sgehrig/symfony,tucksaun/symfony,nicolas-grekas/symfony,curry684/symfony,HeahDude/symfony,ro0NL/symfony,Tobion/symfony,sgehrig/symfony,damienalexandre/symfony,ro0NL/symfony,mpdude/symfony,stof/symfony,ro0NL/symfony,curry684/symfony,nicolas-grekas/symfony,d-ph/symfony,damienalexandre/symfony,symfony/symfony,xabbuh/symfony,symfony/symfony,ogizanagi/symfony,mpdude/symfony,Tobion/symfony,damienalexandre/symfony,nicolas-grekas/symfony,tucksaun/symfony,HeahDude/symfony,derrabus/symfony,mpdude/symfony,derrabus/symfony,paradajozsef/symfony,stof/symfony,symfony/symfony,HeahDude/symfony,d-ph/symfony,d-ph/symfony,damienalexandre/symfony,hhamon/symfony,sgehrig/symfony,derrabus/symfony,xabbuh/symfony,phramz/symfony,phramz/symfony,ogizanagi/symfony,paradajozsef/symfony,curry684/symfony,ogizanagi/symfony,stof/symfony,oleg-andreyev/symfony,ogizanagi/symfony,sgehrig/symfony,phramz/symfony,curry684/symfony,mpdude/symfony,Tobion/symfony,xabbuh/symfony,hhamon/symfony,tucksaun/symfony,hhamon/symfony,nicolas-grekas/symfony,tucksaun/symfony,phramz/symfony,paradajozsef/symfony,hhamon/symfony,d-ph/symfony,oleg-andreyev/symfony