[copy-webpack-plugin] enable dt-header rule.

types/copy-webpack-plugin/index.d.ts

@@ -1,4 +1,4 @@
-// Type definitions for copy-webpack-plugin v4.4.1
+// Type definitions for copy-webpack-plugin 4.4
 // Project: https://github.com/kevlened/copy-webpack-plugin
 // Definitions by: flying-sheep <https://github.com/flying-sheep>
 // Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped

types/copy-webpack-plugin/tslint.json

@@ -7,7 +7,6 @@
         "ban-types": false,
         "callable-types": false,
         "comment-format": false,
-        "dt-header": false,
         "eofline": false,
         "export-just-namespace": false,
         "import-spacing": false,