README: Normalize CircleCI badge styling.
README: Normalize CircleCI badge styling.

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