Archiving drf-openapi-tester

[sondrelg]

It's now been a few years since I've used this personally, so I think I will archive it unless someone else wants to maintain it. Alternative packages like schemathesis have had a lot of development since this was created, so think those generally provide more value for less effort (though it's been a while since I've looked at it).

Opening this in case someone does want to take over maintenance.

@Goldziher, any objections? ☺️