Revert "Merge pull request #136 from boutproject/gridue-to-bout"

Revert adding the gridue_to_bout script here, in favour of including it
in boutdata (boutproject/boutdata#128).

Author: johnomotani

doc/whats-new.md

@@ -33,8 +33,6 @@ Release history
   By [John Omotani](https://github.com/johnomotani)
 - Grids that are nonorthogonal only at the X-point (#180).
   By [John Omotani](https://github.com/johnomotani)
-- Script to convert UEDGE grid file to BOUT++ grid file (#136).
-  By [Ben Dudson](https://github.com/bendudson)
 
 0.5.2 (13th March 2023)
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