Merge pull request #2253 from cpanato/cross

cross: build variants for each k8s release branch (main branch, 1.22, 1.21)

Author: k8s-ci-robot

images/build/cross/variants.yaml

@@ -1,5 +1,5 @@
 variants:
-  go1.17-buster:
+  v1.23-go1.17-buster:
     CONFIG: 'go1.17-buster'
     TYPE: 'default'
     IMAGE_VERSION: 'v1.23.0-go1.17.1-buster.0'
@@ -9,7 +9,7 @@ variants:
     OS_CODENAME: 'buster'
     REVISION: '0'
     PROTOBUF_VERSION: '3.7.0'
-  go1.16-buster:
+  v1.22-go1.16-buster:
     CONFIG: 'go1.16-buster'
     TYPE: 'default'
     IMAGE_VERSION: 'v1.22.0-go1.16.8-buster.0'
@@ -19,6 +19,16 @@ variants:
     OS_CODENAME: 'buster'
     REVISION: '0'
     PROTOBUF_VERSION: '3.7.0'
+  v1.21-go1.16-buster:
+    CONFIG: 'go1.16-buster'
+    TYPE: 'default'
+    IMAGE_VERSION: 'v1.21.0-go1.16.8-buster.0'
+    KUBERNETES_VERSION: 'v1.21.0'
+    GO_VERSION: '1.16.8'
+    GO_MAJOR_VERSION: '1.16'
+    OS_CODENAME: 'buster'
+    REVISION: '0'
+    PROTOBUF_VERSION: '3.7.0'
 
   # TODO: Remove (along with `ETCD_VERSION` in Makefile) once Kubernetes 1.20 is EOL
   go1.15-buster: