debian: add wish to suggests

Debian maintainers already have this and lintian warns us about not
listing 'wish' as a dependency or suggestion so this patch does indeed
just that. The issue, by the way, is that we are shipping hgk (which is
written in tcl/tk) so we should be good citizens and list wish (a meta
package for tcl/tk) as a dependency.

contrib/debian/control

@@ -42,6 +42,7 b' Depends:'
  ${misc:Depends},
  ${python:Depends},
 Recommends: mercurial (= ${source:Version}), ca-certificates
+Suggests: wish
 Breaks: mercurial (<< ${source:Version})
 Replaces: mercurial (<< 2.6.3)
 Description: easy-to-use, scalable distributed version control system (common files)