Fix getting db size for sqlite
Fix getting db size for sqlite

See https://github.com/FreshRSS/FreshRSS/issues/729

Alkarex/FreshRSS,romibi/FreshRSS,romibi/FreshRSS,FreshRSS/FreshRSS,aledeg/FreshRSS,aledeg/FreshRSS,asmundg/FreshRSS,superboum/FreshRSS,samuelstein/FreshRSS,samuelstein/FreshRSS,asmundg/FreshRSS,marienfressinaud/FreshRSS,Alkarex/FreshRSS,aledeg/FreshRSS,FreshRSS/FreshRSS,Alkarex/FreshRSS,aledeg/FreshRSS,Dolomich/FreshRSS,Dolomich/FreshRSS,marienfressinaud/FreshRSS,asmundg/FreshRSS,marienfressinaud/FreshRSS,superboum/FreshRSS,romibi/FreshRSS,Dolomich/FreshRSS,samuelstein/FreshRSS,FreshRSS/FreshRSS,romibi/FreshRSS,superboum/FreshRSS,marienfressinaud/FreshRSS,FreshRSS/FreshRSS,Alkarex/FreshRSS