Upgrade default kind version in get_kind.sh

As mentioned in kubernetes-sigs/kind#2240 there was a change
in the linux kernel after 5.12.2 that makes nf_conntrack_max read-only in non-init network
namespaces, which prevents kind's kube-proxy container from working correctly on kind versions
older than v0.11.1. This PS updates the script to download v0.11.1 to avoid this issue.
If older versions are needed, the kind url can be set as an environment variable as shown in
airshipctl/tools/deployment.provider_common/01_install_kind.sh.

Relates-To: #583
Change-Id: Icd9e649fa112e9f6307034ec69dde5d4a7ad613d

tools/deployment/kind/get_kind.sh

@@ -15,7 +15,7 @@
 # This downloads kind, puts it in a temp directory, and prints the directory
 set -e
 
-: ${KIND_URL:="https://kind.sigs.k8s.io/dl/v0.10.0/kind-$(uname)-amd64"}
+: ${KIND_URL:="https://kind.sigs.k8s.io/dl/v0.11.1/kind-$(uname)-amd64"}
 TMP=$(mktemp -d)
 KIND="${TMP}/kind"