[libfabric-users] RC1 out for libfabric 1.21.0 and 1.20.2

[Xiong, Jianxin]

The first release candidate for the next version (1.21.0) of libfabric & fabtests is available at:

https://github.com/ofiwg/libfabric/releases/tag/v1.21.0rc1

In addition, the first release candidate for bug fix release 1.20.2 of libfabric & fabtests is available at:

https://github.com/ofiwg/libfabric/releases/tag/v1.20.2rc1

-Jianxin