fix(linux): Update launchpad PPA link
fix(linux): Update launchpad PPA link

Update launchpad.sh so that `${tier}` corresponds to the ppa link:
`stable` --> ppa:keymanapp/keyman
others --> ppa:keymanapp/keyman-daily
 ppa depends on the `${tier}`.
tavultesoft/keymanweb,tavultesoft/keymanweb