feat: update k8s and sonobuoy versions

This PR will update k8s to the latest 1.18 release and bump sonobuoy to
help resolve some e2e flakes. Also adds some retry logic around the
sonobuoy run.

Signed-off-by: Spencer Smith <robertspencersmith@gmail.com>

docs/talosctl/talosctl_cluster_create.md

@@ -28,7 +28,7 @@ talosctl cluster create [flags]
       --initrd-path string          the uncompressed kernel image to use (default "_out/initramfs.xz")
   -i, --input-dir string            location of pre-generated config files
       --install-image string        the installer image to use (default "docker.io/autonomy/installer:latest")
-      --kubernetes-version string   desired kubernetes version to run (default "1.18.0")
+      --kubernetes-version string   desired kubernetes version to run (default "1.18.3")
       --masters int                 the number of masters to create (default 1)
       --memory int                  the limit on memory usage in MB (each container) (default 1024)
       --mtu int                     MTU of the docker bridge network (default 1500)

docs/talosctl/talosctl_gen_config.md

@@ -22,7 +22,7 @@ talosctl gen config <cluster name> <cluster endpoint> [flags]
   -h, --help                        help for config
       --install-disk string         the disk to install to (default "/dev/sda")
       --install-image string        the image used to perform an installation (default "docker.io/autonomy/installer:latest")
-      --kubernetes-version string   desired kubernetes version to run (default "1.18.0")
+      --kubernetes-version string   desired kubernetes version to run (default "1.18.3")
   -o, --output-dir string           destination to output generated files
       --registry-mirror strings     list of registry mirrors to use in format: <registry host>=<mirror URL>
       --version string              the desired machine config version to generate (default "v1alpha1")

docs/website/content/v0.4/en/configuration/v1alpha1.md

@@ -35,7 +35,7 @@ machine:
     force: false
 cluster:
   controlPlane:
-    version: 1.18.0
+    version: 1.18.3
     endpoint: https://1.2.3.4
   clusterName: example
   network: