update CHANGELOG, releae 3.4.20
update CHANGELOG, releae 3.4.20

livepy/postgresql,patcon/postgresql,patcon/postgresql,pronix/postgresql,GitBytes/postgresql,hw-cookbooks/postgresql,sous-chefs/postgresql,ozzyogkush/postgresql,chiemi627/postgresql,yakara-ltd/postgresql,Unholster/postgresql,chiemi627/postgresql,rastasheep/postgresql,GitBytes/postgresql,gsaslis/postgresql,pronix/postgresql,Unholster/postgresql,h4ck3rm1k3/postgresql,sous-chefs/postgresql,yakara-ltd/postgresql,gsaslis/postgresql,eheydrick/postgresql,livepy/postgresql,rastasheep/postgresql,h4ck3rm1k3/postgresql,eheydrick/postgresql,hw-cookbooks/postgresql,ozzyogkush/postgresql