util.jsonschema: Fix Lua 5.2 integer compat
math.type() is unavailable before Lua 5.3 so this should use the compat
function added at the top
For full information on our dependencies, version requirements, and
where to find them, see https://prosody.im/doc/depends
If you have luarocks available on your platform, install the following:
- luaexpat
- luasocket
- luafilesystem
- luasec