package: move foreman to nativeCheckInputs

In 1bd195a513 strictDeps was set for the
Hydra package. As a result, `checkInputs` aren't available anymore in
the local dev-shell which is the sole purpose of foreman, to start
services and a database for development.

package.nix

@@ -183,6 +183,7 @@ stdenv.mkDerivation (finalAttrs: {
   nativeCheckInputs = [
     bzip2
     darcs
+    foreman
     top-git
     mercurial
     subversion
@@ -194,7 +195,6 @@ stdenv.mkDerivation (finalAttrs: {
 
   checkInputs = [
     cacert
-    foreman
     glibcLocales
     libressl.nc
     python3