test: Remove i686 from test/get_previous_releases.py
test: Remove i686 from test/get_previous_releases.py

It is not possible to run the compatibility tests on i686 because the
releases v20+ are missing for that arch. It would be possible to
self-compile those releases, but then one can also self-compile
0.15-0.19.

bitcoin/bitcoin,particl/particl-core,jambolo/bitcoin,AkioNak/bitcoin,achow101/bitcoin,ajtowns/bitcoin,lateminer/bitcoin,bitcoin/bitcoin,pataquets/namecoin-core,jamesob/bitcoin,ajtowns/bitcoin,fujicoin/fujicoin,lateminer/bitcoin,fanquake/bitcoin,jamesob/bitcoin,pataquets/namecoin-core,instagibbs/bitcoin,GroestlCoin/GroestlCoin,kallewoof/bitcoin,particl/particl-core,bitcoinsSG/bitcoin,fujicoin/fujicoin,lateminer/bitcoin,ajtowns/bitcoin,anditto/bitcoin,fanquake/bitcoin,achow101/bitcoin,Xekyo/bitcoin,domob1812/bitcoin,anditto/bitcoin,namecoin/namecore,mruddy/bitcoin,bitcoin/bitcoin,anditto/bitcoin,namecoin/namecoin-core,namecoin/namecore,jamesob/bitcoin,mruddy/bitcoin,dscotese/bitcoin,fanquake/bitcoin,pataquets/namecoin-core,lateminer/bitcoin,jlopp/statoshi,namecoin/namecoin-core,GroestlCoin/GroestlCoin,mruddy/bitcoin,sstone/bitcoin,Xekyo/bitcoin,bitcoinsSG/bitcoin,andreaskern/bitcoin,GroestlCoin/GroestlCoin,pataquets/namecoin-core,GroestlCoin/GroestlCoin,kallewoof/bitcoin,particl/particl-core,namecoin/namecore,achow101/bitcoin,AkioNak/bitcoin,dscotese/bitcoin,bitcoinsSG/bitcoin,dscotese/bitcoin,fanquake/bitcoin,jamesob/bitcoin,fujicoin/fujicoin,tecnovert/particl-core,fujicoin/fujicoin,AkioNak/bitcoin,instagibbs/bitcoin,tecnovert/particl-core,sstone/bitcoin,andreaskern/bitcoin,GroestlCoin/bitcoin,bitcoinknots/bitcoin,tecnovert/particl-core,namecoin/namecore,fujicoin/fujicoin,mruddy/bitcoin,GroestlCoin/bitcoin,tecnovert/particl-core,GroestlCoin/GroestlCoin,sipsorcery/bitcoin,sstone/bitcoin,andreaskern/bitcoin,andreaskern/bitcoin,andreaskern/bitcoin,AkioNak/bitcoin,lateminer/bitcoin,GroestlCoin/bitcoin,sipsorcery/bitcoin,kallewoof/bitcoin,AkioNak/bitcoin,lateminer/bitcoin,particl/particl-core,tecnovert/particl-core,namecoin/namecore,namecoin/namecoin-core,jlopp/statoshi,jambolo/bitcoin,bitcoin/bitcoin,namecoin/namecore,GroestlCoin/bitcoin,GroestlCoin/bitcoin,sstone/bitcoin,jambolo/bitcoin,namecoin/namecoin-core,dscotese/bitcoin,bitcoinknots/bitcoin,GroestlCoin/bitcoin,instagibbs/bitcoin,domob1812/bitcoin,jlopp/statoshi,Xekyo/bitcoin,instagibbs/bitcoin,sipsorcery/bitcoin,achow101/bitcoin,namecoin/namecoin-core,dscotese/bitcoin,mruddy/bitcoin,jamesob/bitcoin,jambolo/bitcoin,sipsorcery/bitcoin,pataquets/namecoin-core,sipsorcery/bitcoin,kallewoof/bitcoin,pataquets/namecoin-core,domob1812/bitcoin,anditto/bitcoin,particl/particl-core,Xekyo/bitcoin,domob1812/bitcoin,jlopp/statoshi,namecoin/namecoin-core,bitcoinknots/bitcoin,domob1812/bitcoin,sipsorcery/bitcoin,jamesob/bitcoin,fanquake/bitcoin,bitcoinsSG/bitcoin,bitcoinknots/bitcoin,fujicoin/fujicoin,jlopp/statoshi,AkioNak/bitcoin,jambolo/bitcoin,mruddy/bitcoin,andreaskern/bitcoin,bitcoin/bitcoin,ajtowns/bitcoin,GroestlCoin/GroestlCoin,tecnovert/particl-core,instagibbs/bitcoin,Xekyo/bitcoin,bitcoinknots/bitcoin,anditto/bitcoin,jambolo/bitcoin,bitcoinsSG/bitcoin,ajtowns/bitcoin,Xekyo/bitcoin,kallewoof/bitcoin,fanquake/bitcoin,achow101/bitcoin,jlopp/statoshi,anditto/bitcoin,achow101/bitcoin,domob1812/bitcoin,particl/particl-core,sstone/bitcoin,sstone/bitcoin,bitcoinsSG/bitcoin,ajtowns/bitcoin,dscotese/bitcoin,instagibbs/bitcoin,bitcoin/bitcoin,kallewoof/bitcoin