sys-power/power-profiles-daemon: Run tests sequentially

As dbus tests are known to fail from time to time:
bdb2dba0f8

Closes: https://bugs.gentoo.org/953966
Closes: https://bugs.gentoo.org/954179
Signed-off-by: Pacho Ramos <pacho@gentoo.org>

sys-power/power-profiles-daemon/power-profiles-daemon-0.30.ebuild

@@ -80,6 +80,11 @@ src_configure() {
 	meson_src_configure
 }
 
+src_test() {
+	# Dbus tests are prone to fail when run in parallel
+	MAKEOPTS="-j1" meson_src_test
+}
+
 src_install() {
 	meson_src_install
 	python_fix_shebang "${D}"/usr/bin/powerprofilesctl