Improve Python code: address unused variables (#11049)

* Address F841 (unused variable).

* Reformat.

* Add changelog fragment.

* More cleanup.

* Remove trailing whitespace.

* Readd removed code as a comment with TODO.

plugins/modules/ipmi_boot.py

@@ -177,7 +177,7 @@ def main():
             key = binascii.unhexlify(module.params["key"])
         else:
             key = None
-    except Exception as e:
+    except Exception:
         module.fail_json(msg="Unable to convert 'key' from hex string.")
 
     # --- run command ---