Revert "add path extension func to stdlib-candidate"

This reverts commit b502151.

Author: WindSoilder

stdlib-candidate/nupm.nuon

@@ -3,6 +3,6 @@
     description: "Official candidates for Nushell standard library"
     documentation: "https://github.com/nushell/nu_scripts/blob/main/stdlib-candidate/std-rfc/README.md"
     license: "https://github.com/nushell/nu_scripts/blob/main/LICENSE"
-    version: 0.4.1
+    version: 0.4.0
     type: "module"
 }