Revert "Update textproc/hs-case-insensitive, 1.0.0.1 -> 1.2.0.0."
The latest textproc/hs-case-insensitive was not necessary for textproc/hs-pandoc to build.

This reverts commit 907439009f0e5f5ca351f8eeb2e1fc29c444abcc.