Add PLAYA-PDF and update release dates

[dhdaines]

Hello! Thank you for these benchmarks, I continue to find them useful!

In particular since I have developed PLAYA-PDF, a PDF parsing and analysis library originally based on pdfminer.six but substantially rewritten.

This PR adds PLAYA to the benchmarks, and also updates the versions and release dates for all the other libraries.

Of course the times are not at all the same as on your machine so it might be good to rerun everything.