🐛 Fixed emoji in Slack test notification not rendered by Discord (#9313)
🐛 Fixed emoji in Slack test notification not rendered by Discord (#9313)

closes #9263

- changed emoji for Slack test notification to :smile: which will be correctly rendered as emoji by both, Slack and Discord.

dbalders/Ghost,ErisDS/Ghost,ErisDS/Ghost,acburdine/Ghost,Gargol/Ghost,JohnONolan/Ghost,Kikobeats/Ghost,kevinansfield/Ghost,acburdine/Ghost,Gargol/Ghost,JohnONolan/Ghost,kevinansfield/Ghost,Kikobeats/Ghost,e10/Ghost,janvt/Ghost,TryGhost/Ghost,e10/Ghost,ErisDS/Ghost,TryGhost/Ghost,dbalders/Ghost,dbalders/Ghost,bitjson/Ghost,TryGhost/Ghost,chevex/undoctrinate,acburdine/Ghost,Kikobeats/Ghost,bitjson/Ghost,janvt/Ghost,JohnONolan/Ghost,kevinansfield/Ghost