remove 5.2 branch from PR template
remove 5.2 branch from PR template

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