json: Ensure consistent formatting in api/fixtures.json.
json: Ensure consistent formatting in api/fixtures.json.

Now, the fixtures.json file:
* Has all keys sorted alphabetically.
* Has a space after every `:`.

The file was generated using json.dumps with the appropriate
formatting parameters.

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