mypy: Add 2 Optional[StreamTopicTarget] annotations in actions.py.
mypy: Add 2 Optional[StreamTopicTarget] annotations in actions.py.

kou/zulip,tommyip/zulip,zulip/zulip,rishig/zulip,timabbott/zulip,timabbott/zulip,rishig/zulip,shubhamdhama/zulip,kou/zulip,eeshangarg/zulip,punchagan/zulip,dhcrzf/zulip,showell/zulip,andersk/zulip,eeshangarg/zulip,dhcrzf/zulip,showell/zulip,timabbott/zulip,tommyip/zulip,hackerkid/zulip,andersk/zulip,shubhamdhama/zulip,synicalsyntax/zulip,rishig/zulip,rishig/zulip,showell/zulip,rht/zulip,punchagan/zulip,showell/zulip,rht/zulip,brainwane/zulip,punchagan/zulip,jackrzhang/zulip,timabbott/zulip,rishig/zulip,jackrzhang/zulip,eeshangarg/zulip,dhcrzf/zulip,punchagan/zulip,dhcrzf/zulip,kou/zulip,jackrzhang/zulip,tommyip/zulip,jackrzhang/zulip,tommyip/zulip,punchagan/zulip,brainwane/zulip,kou/zulip,kou/zulip,synicalsyntax/zulip,andersk/zulip,hackerkid/zulip,brainwane/zulip,andersk/zulip,zulip/zulip,zulip/zulip,eeshangarg/zulip,andersk/zulip,showell/zulip,timabbott/zulip,rht/zulip,tommyip/zulip,zulip/zulip,punchagan/zulip,hackerkid/zulip,hackerkid/zulip,brainwane/zulip,dhcrzf/zulip,timabbott/zulip,synicalsyntax/zulip,eeshangarg/zulip,eeshangarg/zulip,shubhamdhama/zulip,dhcrzf/zulip,shubhamdhama/zulip,shubhamdhama/zulip,hackerkid/zulip,jackrzhang/zulip,synicalsyntax/zulip,andersk/zulip,shubhamdhama/zulip,shubhamdhama/zulip,synicalsyntax/zulip,jackrzhang/zulip,rht/zulip,brainwane/zulip,rht/zulip,synicalsyntax/zulip,tommyip/zulip,andersk/zulip,zulip/zulip,kou/zulip,jackrzhang/zulip,timabbott/zulip,rht/zulip,brainwane/zulip,rishig/zulip,hackerkid/zulip,showell/zulip,showell/zulip,brainwane/zulip,synicalsyntax/zulip,kou/zulip,eeshangarg/zulip,rishig/zulip,zulip/zulip,hackerkid/zulip,tommyip/zulip,zulip/zulip,rht/zulip,punchagan/zulip,dhcrzf/zulip