[pre-commit.ci] auto fixes from pre-commit.com hooks

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Examples/Tests/implicit/analysis_vandb_jfnk_2d.py

@@ -17,7 +17,7 @@
 from scipy.constants import e
 from scipy.constants import epsilon_0 as epsilon_0_old
 
-print(f'epsilon_0_old = {epsilon_0_old}')
+print(f"epsilon_0_old = {epsilon_0_old}")
 
 # Use the same value of epsilon_0 as in Source/ablastr/constant.H
 epsilon_0 = 8.8541878128e-12