Advertise support for r0.6.1

[clokep]

Synapse as of #9224 supports r0.6.1 of the Matrix spec, we should advertise support for that.

[turt2live]

just ftr: I've done a quick check against the r0.6.1 spec for what other features synapse might be missing, and found none. Looks very safe to advertise the version.

[aaronraimist]

I don't think Element Web handles the version checks correctly. If you go by the spec

Only the latest Z value will be reported for each supported X.Y value. i.e. if the server implements r0.0.0, r0.0.1, and r1.2.0, it will report r0.0.1 and r1.2.0.

Element will think that the server doesn't support r0.6.0 because the version check is very simplistic. https://github.com/matrix-org/matrix-js-sdk/blob/bbc547fd7f8c7a69e5045f50bbc87c22a9c225bf/src/client.ts#L5806-L5814

Filed as matrix-org/matrix-js-sdk#1984

[turt2live]

The spec is incorrect: the server should be advertising both r0.6.0 and r0.6.1