Update LXQt build dependencies.

debian/changelog

@@ -2,6 +2,7 @@ lxqt-themes (0.15.0-0ubuntu1) UNRELEASED; urgency=medium
 
   * New upstream release.
     - Update upstream signing key.
+    - Update LXQt build dependencies.
   * Update Standards-version to 4.5.0, no changes needed.
 
  -- Simon Quigley <tsimonq2@ubuntu.com>  Thu, 30 Apr 2020 23:48:05 -0500

debian/control

@@ -7,7 +7,7 @@ Section: x11
 Priority: optional
 Build-Depends: debhelper (>= 12),
                cmake,
-               lxqt-build-tools (>= 0.6.0)
+               lxqt-build-tools (>= 0.7.0)
 Standards-Version: 4.5.0
 Vcs-Browser: https://phab.lubuntu.me/source/lxqt-themes/
 Vcs-Git: https://phab.lubuntu.me/source/lxqt-themes.git