Fix typo in Debian package description

Signed-off-by: Sébastien Luttringer <sebastien.luttringer@smartjog.com>

debian/control

@@ -10,7 +10,7 @@ Package: installsystems
 Architecture: all
 Depends: ${misc:Depends}, ${python:Depends}, python-installsystems (>= ${source:Version}), python-psutil (>= 0.2.1)
 XB-Python-Version: ${python:Versions}
-Description: InstallSytems Installer
+Description: InstallSystems Installer
  InstallSystems command line tool
 
 Package: python-installsystems