message view: Fix margin for date separator.
message view: Fix margin for date separator.

Without this tweak the date separator overlaps
the left borner.

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