docker/bake-action v6.6.0

Use bake-action instead of build-and-push action.

docker-bake.hcl

@@ -0,0 +1,19 @@
+group "default" {
+    targets = [ "bookworm", "alpine" ]
+}
+target "_common" {
+    args = {
+        RUBY_VERSION = "3.4.3"
+    }
+}
+
+target "bookworm" {
+    dockerfile = "./dockerfiles/bookworm.Dockerfile"
+    inherits = [ "_common" ]
+    tags = [ "git.kill0.net/ryanc/kubernaut" ]
+}
+
+target "alpine" {
+    dockerfile = "./dockerfiles/alpine.Dockerfile"
+    inherits = [ "_common" ]
+}