add missing n4 instance types (#357)

Co-authored-by: sebastiandero <sebastiandero@users.noreply.github.com>

Author: sebastiandero

rules/utils.go

@@ -221,6 +221,33 @@ var validMachineTypes = map[string]bool{
 	"n2d-highcpu-96":   true,
 	"n2d-highcpu-128":  true,
 	"n2d-highcpu-224":  true,
+
+	//n4
+	"n4-standard-2":  true,
+	"n4-standard-4":  true,
+	"n4-standard-8":  true,
+	"n4-standard-16": true,
+	"n4-standard-32": true,
+	"n4-standard-48": true,
+	"n4-standard-64": true,
+	"n4-standard-80": true,
+	"n4-highcpu-2":   true,
+	"n4-highcpu-4":   true,
+	"n4-highcpu-8":   true,
+	"n4-highcpu-16":  true,
+	"n4-highcpu-32":  true,
+	"n4-highcpu-48":  true,
+	"n4-highcpu-64":  true,
+	"n4-highcpu-80":  true,
+	"n4-highmem-2":   true,
+	"n4-highmem-4":   true,
+	"n4-highmem-8":   true,
+	"n4-highmem-16":  true,
+	"n4-highmem-32":  true,
+	"n4-highmem-48":  true,
+	"n4-highmem-64":  true,
+	"n4-highmem-80":  true,
+
 	// T2
 	"t2a-standard-1":  true,
 	"t2a-standard-2":  true,