settings: Fix missing typing import.
settings: Fix missing typing import.

The world previously passed CI only because old versions of
prod_settings_template have this already present via the * import.

punchagan/zulip,zulip/zulip,timabbott/zulip,timabbott/zulip,hackerkid/zulip,andersk/zulip,brainwane/zulip,shubhamdhama/zulip,synicalsyntax/zulip,brainwane/zulip,eeshangarg/zulip,kou/zulip,timabbott/zulip,hackerkid/zulip,timabbott/zulip,timabbott/zulip,andersk/zulip,andersk/zulip,shubhamdhama/zulip,punchagan/zulip,shubhamdhama/zulip,brainwane/zulip,andersk/zulip,showell/zulip,synicalsyntax/zulip,punchagan/zulip,brainwane/zulip,andersk/zulip,synicalsyntax/zulip,kou/zulip,hackerkid/zulip,eeshangarg/zulip,rht/zulip,eeshangarg/zulip,showell/zulip,kou/zulip,rht/zulip,kou/zulip,brainwane/zulip,eeshangarg/zulip,hackerkid/zulip,punchagan/zulip,timabbott/zulip,synicalsyntax/zulip,rht/zulip,hackerkid/zulip,shubhamdhama/zulip,hackerkid/zulip,rht/zulip,zulip/zulip,zulip/zulip,showell/zulip,andersk/zulip,kou/zulip,eeshangarg/zulip,eeshangarg/zulip,rht/zulip,synicalsyntax/zulip,timabbott/zulip,punchagan/zulip,zulip/zulip,kou/zulip,eeshangarg/zulip,shubhamdhama/zulip,synicalsyntax/zulip,zulip/zulip,zulip/zulip,rht/zulip,showell/zulip,hackerkid/zulip,showell/zulip,zulip/zulip,punchagan/zulip,andersk/zulip,showell/zulip,rht/zulip,brainwane/zulip,brainwane/zulip,synicalsyntax/zulip,showell/zulip,kou/zulip,shubhamdhama/zulip,shubhamdhama/zulip,punchagan/zulip