v0.6.0

Thanks to (@dyashuni) hnswlib now uses github actions for CI, there is a search speedup in some scenarios with deletions. unmark_deleted(label) is now also a part of the python interface (note now it throws an exception for double deletions).
Thanks to (@slice4e) we now support AVX512; thanks to (@LTLA) the cmake interface for the lib is now updated.
Thanks to (@alonre24) we now have a python bindings for brute-force (and examples for recall tuning: TESTING_RECALL.md.
Thanks to (@dorosy-yeong) there is a bug fixed in the handling large quantities of deleted elements and large K.