Provide a compatibility matrix for PG, TSDB, Extension, Connector versions

[JamesGuthrie]

We currently don't surface to users which versions of these components work together.

[paulfantom]

Also this matrix should be reflected by tests running in CI. Basically if we don't test it, it's not supported.

[niksajakovljevic]

I believe that compatibility between PG, TSDB and Promscale Extension should be solved inside Promscale Extension. Connector then should define compatibilty with Extension version only. This way we separate concerns. Imho Connector should be as much as possible isolated from DB specifics and it should not force specific PG, TSDB versions - that's more for the Extension.

[antekresic]

Promscale version compatibility matrix

Connector	Extension	TSDB	Postgres
0.12.x	0.5.x	2.6.1 and above*	12.x, 13.x, 14.x
0.11.x	0.5.x	2.6.1 and above*	12.x, 13.x, 14.x
0.10.x	up to 0.3.2**	1.7.3 and above**	12.x, 13.x, 14.x
0.9.x	up to 0.3.2**	1.7.3 and above**	12.x, 13.x, 14.x

* single-node only ** optional

[cevian]

^ @antekresic's chart looks right. I would suggest changing 0.5.0 and above to 0.5.x for the extension version since I am not sure we want to commit to indefinite backwards compatibility.