update containerd binary to v1.3.9 (address CVE-2020-15257)

full diff: https://github.com/containerd/containerd/compare/v1.3.8...v1.3.9

Release notes:

containerd 1.3.9
---------------------

Welcome to the v1.3.9 release of containerd!

The ninth patch release for containerd 1.3 is a security release to address
CVE-2020-15257. See GHSA-36xw-fx78-c5r4 for more details:
https://github.com/containerd/containerd/security/advisories/GHSA-36xw-fx78-c5r4

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
diff --git a/hack/dockerfile/install/containerd.installer b/hack/dockerfile/install/containerd.installer
index dedf997..f7ead97 100755
--- a/hack/dockerfile/install/containerd.installer
+++ b/hack/dockerfile/install/containerd.installer
@@ -4,7 +4,7 @@
 # containerd is also pinned in vendor.conf. When updating the binary
 # version you may also need to update the vendor version to pick up bug
 # fixes or new APIs.
-: "${CONTAINERD_COMMIT:=7fb6e171309113ddcb8ea9599e34321550469250}" # v1.3.8
+: "${CONTAINERD_COMMIT:=ea765aba0d05254012b0b9e595e995c09186427f}" # v1.3.9
 
 install_containerd() {
 	echo "Install containerd version $CONTAINERD_COMMIT"