I tried to install tensorflow today on a system running CentOS 8 and the latest CUDA toolkit for 10.1 (v243) available on the Nvidia rpm repository miss the libcublas library (available only from 10.2).
I solved the issue installing an older version of CUDA 10.1:
As it was mentioned in the 1st comment cublas to be outside of the toolkit installation path (for some reason…). And after installation of cuda-10.1 (v243) it seems that it really doesnt appear in cuda libs (e.g. /usr/local/cuda-10.1/lib64 or /usr/lib/x86_64-linux-gnu/).