Fixed UP032 (f-string): Use f-string instead of format call

management/utils.py

@@ -22,7 +22,7 @@ def load_env_vars_from_file(fn):
 def save_environment(env):
     with open("/etc/mailinabox.conf", "w") as f:
         for k, v in env.items():
-            f.write("{}={}\n".format(k, v))
+            f.write(f"{k}={v}\n")
 
 # THE SETTINGS FILE AT STORAGE_ROOT/settings.yaml.