gnu: ganeti: Use pandoc instead of ghc-pandoc.

* gnu/packages/text-editors.scm (ganeti)[native-inputs]: Replace ghc-pandoc
with pandoc.

Signed-off-by: Ludovic Courtès <ludo@gnu.org>

gnu/packages/virtualization.scm

@@ -679,7 +679,7 @@ server and embedded PowerPC, and S390 guests.")
        ;; For the documentation.
        ("python-docutils" ,python-docutils)
        ("sphinx" ,python-sphinx)
-       ("pandoc" ,ghc-pandoc)
+       ("pandoc" ,pandoc)
        ("dot" ,graphviz)
 
        ;; Test dependencies.