[SDK] PinnedTrustManager checks only one item from certificates chain

When implementing chat functionality for a client I've faced issue with certificate pinning in matrix sdk. I have server root certificate fingerprint, which I pass to config via `withAllowedFingerPrints` method, I set 'withPin' option, but still all requests ends up with `UnrecognizedCertificateException`.

Problem is caused by the thing, that on the server side we use Let's encrypt with short living certificates at the bottom of the chain, and `PinnedTrustManagerApi24` in `checkTrusted' checks only that last certificate instead of going up through the chain till it meets root certificate, like from my understanding it should do.

So I think it's a bug, that mentioned method checks only last item of the chain, instead of going through whole certificates chain and test if any of them matches allowed fingerprints.