Bump version to v2.0.0rc2 (open-mmlab#2349)

* Bump version to v2.0.0rc2

* minor refine

Bump version to v1.6.2 (open-mmlab#2285)

Bump version to v2.0.0rc1 (open-mmlab#2240)

bump version to v1.6.1 (open-mmlab#2142)

Bump version to v1.6.0 (open-mmlab#2096)

* bump version to v1.6.0

* minor fix

Bump version to v1.5.3 (open-mmlab#2053)

Fix lint (open-mmlab#1984)

[Fix] Fix bbox overlap fp16 (open-mmlab#1958)

* add CUDA_ARCH check

* add check in cuh

bump version to v1.5.0 (open-mmlab#1883)

bump version to v1.4.8 (open-mmlab#1836)