Cirrus-CI: forcably upgrade pkg to latest

make packages requires the latest pkg for now so force that.

Differential Revision:	https://reviews.freebsd.org/D42908

.cirrus.yml

@@ -75,6 +75,11 @@ task:
   install_script:
   - sh .cirrus-ci/pkg-install.sh ${TOOLCHAIN_PKG} git-lite
 
+  xxx_upgrade_pkg_script:
+  - fetch http://pkg.freebsd.org/FreeBSD:13:amd64/latest/All/pkg-1.20.9.pkg
+  - pkg install -y ./pkg-1.20.9.pkg
+  - rm -f pkg-1.20.9.pkg
+
   setup_script:
   - uname -a
   - gpart show