feat(rds): add postgres engine 16.8, 15.12, 14.17 and 13.20

Author: phuhung273

packages/aws-cdk-lib/aws-rds/lib/cluster-engine.ts

@@ -1024,6 +1024,8 @@ export class AuroraPostgresEngineVersion {
   public static readonly VER_13_16 = AuroraPostgresEngineVersion.of('13.16', '13', { s3Import: true, s3Export: true });
   /** Version "13.17". */
   public static readonly VER_13_17 = AuroraPostgresEngineVersion.of('13.17', '13', { s3Import: true, s3Export: true });
+  /** Version "13.20". */
+  public static readonly VER_13_20 = AuroraPostgresEngineVersion.of('13.20', '13', { s3Import: true, s3Export: true });
   /** Version "13.18". */
   public static readonly VER_13_18 = AuroraPostgresEngineVersion.of('13.18', '13', { s3Import: true, s3Export: true });
   /** Version "14.3". */
@@ -1052,6 +1054,8 @@ export class AuroraPostgresEngineVersion {
   public static readonly VER_14_14 = AuroraPostgresEngineVersion.of('14.14', '14', { s3Import: true, s3Export: true });
   /** Version "14.15". */
   public static readonly VER_14_15 = AuroraPostgresEngineVersion.of('14.15', '14', { s3Import: true, s3Export: true });
+  /** Version "14.17". */
+  public static readonly VER_14_17 = AuroraPostgresEngineVersion.of('14.17', '14', { s3Import: true, s3Export: true });
   /** Version "15.2". */
   public static readonly VER_15_2 = AuroraPostgresEngineVersion.of('15.2', '15', { s3Import: true, s3Export: true });
   /** Version "15.3". */
@@ -1070,6 +1074,8 @@ export class AuroraPostgresEngineVersion {
   public static readonly VER_15_9 = AuroraPostgresEngineVersion.of('15.9', '15', { s3Import: true, s3Export: true });
   /** Version "15.10". */
   public static readonly VER_15_10 = AuroraPostgresEngineVersion.of('15.10', '15', { s3Import: true, s3Export: true });
+  /** Version "15.12". */
+  public static readonly VER_15_12 = AuroraPostgresEngineVersion.of('15.12', '15', { s3Import: true, s3Export: true });
   /**
    * Version "16.0"
    * @deprecated Version 16.0 is no longer supported by Amazon RDS.
@@ -1091,6 +1097,8 @@ export class AuroraPostgresEngineVersion {
   public static readonly VER_16_6 = AuroraPostgresEngineVersion.of('16.6', '16', { s3Import: true, s3Export: true });
   /** Version "16.6 limitless" */
   public static readonly VER_16_6_LIMITLESS = AuroraPostgresEngineVersion.of('16.6-limitless', '16', { s3Import: true, s3Export: true });
+  /** Version "16.8". */
+  public static readonly VER_16_8 = AuroraPostgresEngineVersion.of('16.8', '16', { s3Import: true, s3Export: true });
   /** Version "17.1". */
   public static readonly VER_17_1 = AuroraPostgresEngineVersion.of('17.1', '17', { s3Import: true, s3Export: true });
   /** Version "17.2". */