[BUG] --enable_alpha_plugins is now --enable-alpha-plugins in Kustomize 4.0.1

[Lawouach]

Describe the bug

Kustomize 4 has renamed the flag --enable_alpha_plugins to --enable-alpha-plugins meaning this action fails with Kustomize 4+

https://github.com/kubernetes-sigs/kustomize/commit/6cf48442df1315a5269fc2267cebe7a0c6475edf

To Reproduce Use Kustomize 4.1.3 for instance:

Expected behavior

Both flag versions ought be supported.

[karancode]

Thank you @Lawouach for reporting this. Feel free to take it up otherwise I will work on it in a while.