message: bumped up HiOp version requirement
diff: @@ -692,7 +692,7 @@ The specific libraries and their options are:
  - HiOp (optional), used when MFEM_USE_HIOP = YES.
  URL: https://github.com/LLNL/hiop
  Options: HIOP_OPT, HIOP_LIB.
  - Versions: HIOP >= 0.4.
  + Versions: HIOP >= 0.4.6.
  - GSLIB (optional), used when MFEM_USE_GSLIB = YES. The gslib library must be
  built prior to the MFEM build, as follows: download gslib-1.0.7, untar it at
  