push_notifications: Fix mypy error.
push_notifications: Fix mypy error.

showell/zulip,synicalsyntax/zulip,timabbott/zulip,showell/zulip,andersk/zulip,brainwane/zulip,kou/zulip,jackrzhang/zulip,amanharitsh123/zulip,Galexrt/zulip,punchagan/zulip,showell/zulip,dhcrzf/zulip,amanharitsh123/zulip,synicalsyntax/zulip,rishig/zulip,andersk/zulip,hackerkid/zulip,verma-varsha/zulip,showell/zulip,hackerkid/zulip,showell/zulip,hackerkid/zulip,dhcrzf/zulip,kou/zulip,shubhamdhama/zulip,punchagan/zulip,kou/zulip,zulip/zulip,rht/zulip,Galexrt/zulip,punchagan/zulip,amanharitsh123/zulip,brainwane/zulip,synicalsyntax/zulip,brainwane/zulip,timabbott/zulip,amanharitsh123/zulip,punchagan/zulip,dhcrzf/zulip,verma-varsha/zulip,dhcrzf/zulip,rht/zulip,mahim97/zulip,rht/zulip,amanharitsh123/zulip,shubhamdhama/zulip,synicalsyntax/zulip,Galexrt/zulip,synicalsyntax/zulip,mahim97/zulip,brockwhittaker/zulip,brockwhittaker/zulip,hackerkid/zulip,andersk/zulip,rht/zulip,shubhamdhama/zulip,mahim97/zulip,timabbott/zulip,zulip/zulip,dhcrzf/zulip,jackrzhang/zulip,hackerkid/zulip,punchagan/zulip,amanharitsh123/zulip,verma-varsha/zulip,brainwane/zulip,rishig/zulip,tommyip/zulip,verma-varsha/zulip,eeshangarg/zulip,punchagan/zulip,eeshangarg/zulip,shubhamdhama/zulip,verma-varsha/zulip,rishig/zulip,shubhamdhama/zulip,tommyip/zulip,hackerkid/zulip,showell/zulip,brainwane/zulip,brainwane/zulip,rht/zulip,tommyip/zulip,eeshangarg/zulip,hackerkid/zulip,brockwhittaker/zulip,showell/zulip,timabbott/zulip,eeshangarg/zulip,rht/zulip,eeshangarg/zulip,jackrzhang/zulip,dhcrzf/zulip,andersk/zulip,rishig/zulip,tommyip/zulip,tommyip/zulip,brockwhittaker/zulip,andersk/zulip,timabbott/zulip,shubhamdhama/zulip,jackrzhang/zulip,andersk/zulip,rht/zulip,punchagan/zulip,brainwane/zulip,brockwhittaker/zulip,zulip/zulip,dhcrzf/zulip,zulip/zulip,zulip/zulip,Galexrt/zulip,shubhamdhama/zulip,zulip/zulip,mahim97/zulip,synicalsyntax/zulip,tommyip/zulip,timabbott/zulip,eeshangarg/zulip,mahim97/zulip,brockwhittaker/zulip,rishig/zulip,Galexrt/zulip,kou/zulip,andersk/zulip,kou/zulip,kou/zulip,eeshangarg/zulip,timabbott/zulip,kou/zulip,jackrzhang/zulip,mahim97/zulip,synicalsyntax/zulip,rishig/zulip,Galexrt/zulip,rishig/zulip,tommyip/zulip,Galexrt/zulip,jackrzhang/zulip,jackrzhang/zulip,verma-varsha/zulip,zulip/zulip