Make `get_experiment_list_from_gene` case insensitive

[jankrepl]

Atlas-Download-Tools/src/atldld/utils.py

Line 205 in b08093f

def get_experiment_list_from_gene(gene_name, axis="sagittal"):

The motivation behind making the search case insensitive is that the web interface is also case insensitive. http://mouse.brain-map.org/

However, it is not a must