comment out license field in package.yaml for avoiding errors

Specifying 'license: GPL-3.0-or-later' generate cabal file with
'cabal-version: 2.2' which causes error to old version of Cabal
library and also hpack seems not to generate required
'autogen-modules' field.

MIP-glpk/package.yaml

@@ -1,7 +1,7 @@
 name:                MIP-glpk
 version:             0.1.1.0
 github:              "msakai/haskell-MIP"
-license:             GPL-3.0-or-later
+# license:             GPL-3.0-or-later
 license-file:        COPYING
 author:              "Masahiro Sakai"
 maintainer:          "masahiro.sakai@gmail.com"