remove "CHANNEL=test" check for docker-buildx-plugin

Now that docker 22.06 and the docker-buildx-plugin is available in the stable
channel, we no longer need this check.

NOTE: technically, it's possible to install the buildx plugin on older
      versions as well (it will replace the bundled buildx plugin), so
      we could consider changing the version to (e.g.) 20.10, same as
      we did for docker compose.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

install.sh

@@ -444,8 +444,7 @@ do_install() {
 						# also install the latest version of the "docker scan" cli-plugin (only supported on x86 currently)
 						pkgs="$pkgs docker-scan-plugin"
 				fi
-				# TODO(thaJeztah) remove the $CHANNEL check once 22.06 and docker-buildx-plugin is published to the "stable" channel
-				if [ "$CHANNEL" = "test" ] && version_gte "22.06"; then
+				if version_gte "22.06"; then
 						pkgs="$pkgs docker-buildx-plugin"
 				fi
 				if ! is_dry_run; then
@@ -540,8 +539,7 @@ do_install() {
 				if version_gte "20.10"; then
 					pkgs="$pkgs docker-compose-plugin docker-ce-rootless-extras$pkg_version"
 				fi
-				# TODO(thaJeztah) remove the $CHANNEL check once 22.06 and docker-buildx-plugin is published to the "stable" channel
-				if [ "$CHANNEL" = "test" ] && version_gte "22.06"; then
+				if version_gte "22.06"; then
 						pkgs="$pkgs docker-buildx-plugin"
 				fi
 				if ! is_dry_run; then
@@ -624,8 +622,7 @@ do_install() {
 				if version_gte "20.10"; then
 					pkgs="$pkgs docker-compose-plugin docker-ce-rootless-extras$pkg_version"
 				fi
-				# TODO(thaJeztah) remove the $CHANNEL check once 22.06 and docker-buildx-plugin is published to the "stable" channel
-				if [ "$CHANNEL" = "test" ] && version_gte "22.06"; then
+				if version_gte "22.06"; then
 						pkgs="$pkgs docker-buildx-plugin"
 				fi
 				if ! is_dry_run; then