README: Remove provider version

- If users copy/paste this without changing anything, they'll be on a super early version.

Author: issyl0

README.md

@@ -20,7 +20,6 @@ terraform {
   required_providers {
     improvmx = {
       source  = "issyl0/improvmx"
-      version = "0.1.0"
     }
   }
 }