[doc] Black-fy

doc/conf.py

@@ -234,7 +234,7 @@ intersphinx_mapping = {
 
 # Doctest global setup
 sphinx_source_dir = os.path.abspath(".")
-doctest_global_setup = f'''
+doctest_global_setup = f"""
 import os
 data = os.path.join('{sphinx_source_dir}', 'data')
-'''
+"""