chore(rds): add MariaDB ver 10.5.12, 10.4.21, 10.3.31, 10.2.40 and Au…

…rora Postgres ver 13.3 (#16466)

Add new RDS versions:

**MariaDbEngineVersion 10.5.12, 10.4.21, 10.3.31, 10.2.40**
Announcement: https://aws.amazon.com/about-aws/whats-new/2021/09/amazon-rds-mariadb-new-minor-versions/

**AuroraPostgresEngineVersion 13.3**
Announcement: https://aws.amazon.com/about-aws/whats-new/2021/08/amazon-aurora-postgresql-13/
According to AWS CLI and AWS Console, the exact EngineVersion is 13.3.
s3Export and s3Import are supported, see command `aws rds describe-db-engine-versions --region us-east-1 --engine aurora-postgresql --engine-version 13`.

----

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

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

@@ -465,6 +465,8 @@ export class AuroraPostgresEngineVersion {
   public static readonly VER_12_4 = AuroraPostgresEngineVersion.of('12.4', '12', { s3Import: true, s3Export: true });
   /** Version "12.6". */
   public static readonly VER_12_6 = AuroraPostgresEngineVersion.of('12.6', '12', { s3Import: true, s3Export: true });
+  /** Version "13.3". */
+  public static readonly VER_13_3 = AuroraPostgresEngineVersion.of('13.3', '13', { s3Import: true, s3Export: true });
 
   /**
    * Create a new AuroraPostgresEngineVersion with an arbitrary version.

packages/@aws-cdk/aws-rds/lib/instance-engine.ts

@@ -249,6 +249,8 @@ export class MariaDbEngineVersion {
   public static readonly VER_10_2_37 = MariaDbEngineVersion.of('10.2.37', '10.2');
   /** Version "10.2.39". */
   public static readonly VER_10_2_39 = MariaDbEngineVersion.of('10.2.39', '10.2');
+  /** Version "10.2.40". */
+  public static readonly VER_10_2_40 = MariaDbEngineVersion.of('10.2.40', '10.2');
 
   /** Version "10.3" (only a major version, without a specific minor version). */
   public static readonly VER_10_3 = MariaDbEngineVersion.of('10.3', '10.3');
@@ -262,6 +264,8 @@ export class MariaDbEngineVersion {
   public static readonly VER_10_3_23 = MariaDbEngineVersion.of('10.3.23', '10.3');
   /** Version "10.3.28". */
   public static readonly VER_10_3_28 = MariaDbEngineVersion.of('10.3.28', '10.3');
+  /** Version "10.3.31". */
+  public static readonly VER_10_3_31 = MariaDbEngineVersion.of('10.3.31', '10.3');
 
   /** Version "10.4" (only a major version, without a specific minor version). */
   public static readonly VER_10_4 = MariaDbEngineVersion.of('10.4', '10.4');
@@ -271,13 +275,17 @@ export class MariaDbEngineVersion {
   public static readonly VER_10_4_13 = MariaDbEngineVersion.of('10.4.13', '10.4');
   /** Version "10.4.18". */
   public static readonly VER_10_4_18 = MariaDbEngineVersion.of('10.4.18', '10.4');
+  /** Version "10.4.21". */
+  public static readonly VER_10_4_21 = MariaDbEngineVersion.of('10.4.21', '10.4');
 
   /** Version "10.5" (only a major version, without a specific minor version). */
   public static readonly VER_10_5 = MariaDbEngineVersion.of('10.5', '10.5');
   /** Version "10.5.8". */
   public static readonly VER_10_5_8 = MariaDbEngineVersion.of('10.5.8', '10.5');
   /** Version "10.5.9". */
   public static readonly VER_10_5_9 = MariaDbEngineVersion.of('10.5.9', '10.5');
+  /** Version "10.5.12". */
+  public static readonly VER_10_5_12 = MariaDbEngineVersion.of('10.5.12', '10.5');
 
   /**
    * Create a new MariaDbEngineVersion with an arbitrary version.