plasma-pa: remove GConf dependecy

GConf is obsolete and shouldn't be used anymore, the functionality loss
for plasma-pa is minimal https://phabricator.kde.org/D13734

srcpkgs/plasma-pa/template

@@ -1,13 +1,13 @@
 # Template file for 'plasma-pa'
 pkgname=plasma-pa
 version=5.14.4
-revision=1
+revision=2
 build_style=cmake
 configure_args="-DBUILD_TESTING=OFF"
 hostmakedepends="extra-cmake-modules kcoreaddons kdoctools pkg-config
  qt5-host-tools qt5-qmake"
 makedepends="plasma-framework-devel kdoctools-devel pulseaudio-devel
- GConf-devel libcanberra-devel"
+ libcanberra-devel"
 short_desc="PulseAudio Plasma applet"
 maintainer="Denis Revin <denis.revin@gmail.com>"
 license="LGPL-2.1-or-later"