Add and apply Lint/NonAtomicFileOperation rule

This rule was added in Rubocop 1.31.0; it follows the principles
mentioned in the Ruby Style Guide [1].

https://rubystyle.guide/#atomic-file-operations

.rubocop.yml

@@ -179,6 +179,9 @@ Lint/EmptyFile:
 Lint/LiteralAsCondition:
   Enabled: true
 
+Lint/NonAtomicFileOperation:
+  Enabled: true
+
 Lint/ParenthesesAsGroupedExpression:
   Enabled: true