Incorrect error with missing extension permissions

[cd-work]

Currently the following error is printed when permissions are missing for executing an extension:

❗ Error: Execution failed caused by: Error: Requires write access to "./duplicates.txt", run again with the --allow-write flag

This makes it sound like the error could be fixed by adding the --alow-write flag to the extension, however this is a Deno CLI feature which is unrelated to the Phylum CLI extensions.

To avoid confusion, we should rephrase this error to remove the confusing flag reference and potentially indicate that the extension requires updating to fix this.

The extension documentation should also be updated, since it currently contains the old error.