Fix lintian errors

Signed-off-by: Vignesh Raman <vignesh.raman@collabora.com>

debian/apertis-dev-tools.lintian-overrides

+# apertis-dev-tools does not provide manpages for the tools yet.
+no-manual-page
+

debian/control

 Source: apertis-dev-tools
 Section: devel
-Priority: extra
+Priority: optional
 Maintainer: Apertis package maintainers <packagers@lists.apertis.org>
 Build-Depends:
  debhelper (>= 9),
@@ -21,7 +21,7 @@ Architecture: all
 Depends:
  ${shlibs:Depends},
  ${misc:Depends},
- ${pythons3:Depends},
+ ${python3:Depends},
  abi-compliance-checker,
  flatpak,
  git-buildpackage,

debian/rules

@@ -4,7 +4,7 @@
 # export DH_VERBOSE=1
 
 %:
-	dh $@
+	dh $@ --with-python3
 
 override_dh_auto_install:
 	dh_auto_install --destdir=debian/tmp