[pkg] add Replaces: bitmask to debian/control

debian/changelog

+riseup-vpn (0.19.2-3) unstable; urgency=medium
+
+  * d/control: add Replaces: bitmask
+
+ -- Micah Anderson <user@localhost>  Wed, 04 Sep 2019 09:14:59 -0400
+
 riseup-vpn (0.19.2-2) unstable; urgency=medium
 
   * Update copyright to fix GPL-3+ name

debian/control

@@ -16,6 +16,7 @@ Depends: ${shlibs:Depends}, ${misc:Depends},
     policykit-1-gnome | polkit-1-auth-agent,
     ${python:Depends}
 Enhances: openvpn
+Replaces: bitmask
 Description: Easy, fast, and secure VPN service from Riseup.
  This package is a custom build of the new Bitmask VPN client, preconfigured
  to use the https://riseup.net provider.