Replace format and % strings with f-strings
Replace format and % strings with f-strings

* wqflask/wqflask/marker_regression/gemma_mapping.py: Use f-strings
which are easier to read.
(generate_random_n_string): New function.

zsloan/genenetwork2,zsloan/genenetwork2,pjotrp/genenetwork2,genenetwork/genenetwork2,genenetwork/genenetwork2,zsloan/genenetwork2,pjotrp/genenetwork2,pjotrp/genenetwork2,genenetwork/genenetwork2,pjotrp/genenetwork2,zsloan/genenetwork2,pjotrp/genenetwork2,genenetwork/genenetwork2