bump debhelper to 12 (available in buster), no longer need --parallel

debian/configure

@@ -86,8 +86,8 @@ PYTHON_IMAGING=python3-pil
 PYTHON_IMAGING_TK=python3-pil.imagetk
 QTVCP_DEPENDS="python3-pyqt5,\n    python3-pyqt5.qsci,\n    python3-pyqt5.qtsvg,\n    python3-pyqt5.qtopengl,\n    python3-opencv,\n    python3-dbus,python3-espeak,\n    python3-dbus.mainloop.pyqt5,\n    python3-pyqt5.qtwebkit,\n    espeak-ng,\n    pyqt5-dev-tools,\n    gstreamer1.0-tools,espeak,\n    sound-theme-freedesktop"
 YAPPS_RUNTIME="python3-yapps"
-DEBHELPER="debhelper (>= 9)"
-COMPAT="9"
+DEBHELPER="debhelper (>= 12)"
+COMPAT="12"
 
 case $DISTRIB_NAME in
     Ubuntu-21.*|Debian-11|Debian-11.*|Debian-testing|Debian-unstable)

debian/rules.in

@@ -35,8 +35,7 @@ DESTDIR=$(CURDIR)/debian/tmp
 DEV_PACKAGE_NAME=@MAIN_PACKAGE_NAME@-dev
 
 %:
-	# With debhelper 10 the --parallel becomes the default
-	dh $@ --parallel
+	dh $@
 
 override_dh_auto_configure:
 	cd src && ./autogen.sh

debian/source/lintian-overrides

@@ -1,5 +1,2 @@
 # False positive - python3 is invoked in d/rules.
 linuxcnc source: python3-depends-but-no-python3-helper linuxcnc-uspace linuxcnc-uspace-dev
-
-# For the early versions of debhelper (<10) this is not unnecessary
-linuxcnc source: debian-rules-uses-unnecessary-dh-argument dh ... --parallel (line 32)