test: bump OLM to 0.20.0

Author: pohly

test/start-stop-olm.sh

@@ -18,8 +18,7 @@ SSH="${CLUSTER_DIR}/ssh.0"
 KUBECTL="${SSH} kubectl" # Always use the kubectl installed in the cluster.
 
 # https://github.com/operator-framework/operator-lifecycle-manager/releases
-# Not the latest because of https://github.com/operator-framework/operator-sdk/issues/5410
-OLM_VERSION=v0.18.3
+OLM_VERSION=v0.20.0
 
 function usage() {
     echo "Usage:"