feat(rds): add Aurora MySQL versions 2.12.4, 3.08.2

[Tietew]

Reason for this change

New Aurora MySQL versions are available.

• 2.12.4 - Database engine updates for Amazon Aurora MySQL version 2
• 3.08.2 - Database engine updates for Amazon Aurora MySQL version 3

Note: Release note for 3.08.2 is missing currently, but describe-db-engine-versions API tells it's available now (see below).

Description of changes

Added above Aurora MySQL versions.

Describe any new or updated permissions being added

N/A

Description of how you validated changes

$ aws --region us-east-1 rds describe-db-engine-versions --engine aurora-mysql --query DBEngineVersions[].EngineVersion
[
    "5.7.mysql_aurora.2.11.1",
    "5.7.mysql_aurora.2.11.2",
    "5.7.mysql_aurora.2.11.3",
    "5.7.mysql_aurora.2.11.4",
    "5.7.mysql_aurora.2.11.5",
    "5.7.mysql_aurora.2.11.6",
    "5.7.mysql_aurora.2.12.0",
    "5.7.mysql_aurora.2.12.1",
    "5.7.mysql_aurora.2.12.2",
    "5.7.mysql_aurora.2.12.3",
    "5.7.mysql_aurora.2.12.4",
    "8.0.mysql_aurora.3.04.0",
    "8.0.mysql_aurora.3.04.1",
    "8.0.mysql_aurora.3.04.2",
    "8.0.mysql_aurora.3.04.3",
    "8.0.mysql_aurora.3.05.2",
    "8.0.mysql_aurora.3.06.0",
    "8.0.mysql_aurora.3.06.1",
    "8.0.mysql_aurora.3.07.0",
    "8.0.mysql_aurora.3.07.1",
    "8.0.mysql_aurora.3.08.0",
    "8.0.mysql_aurora.3.08.1",
    "8.0.mysql_aurora.3.08.2"
]

Checklist

• My code adheres to the CONTRIBUTING GUIDE and DESIGN GUIDELINES

---

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

[aws-cdk-automation]

The pull request linter fails with the following errors:

❌ Features must contain a change to a README file.
❌ Features must contain a change to a test file.
❌ Features must contain a change to an integration test file and the resulting snapshot.

If you believe this pull request should receive an exemption, please comment and provide a justification. A comment requesting an exemption should contain the text Exemption Request. Additionally, if clarification is needed, add Clarification Request to a comment.

✅ A exemption request has been requested. Please wait for a maintainer's review.

[Tietew]

Exemption Request: README and tests are not required generally when adding new engine versions.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 83.98%. Comparing base (994e952) to head (a847497).

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #34045   +/-   ##
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  Coverage   83.98%   83.98%           
=======================================
  Files         120      120           
  Lines        6976     6976           
  Branches     1178     1178           
=======================================
  Hits         5859     5859           
  Misses       1005     1005           
  Partials      112      112           

Flag	Coverage Δ
suite.unit	83.98% <ø> (ø)

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Components	Coverage Δ
packages/aws-cdk	∅ <ø> (∅)
packages/aws-cdk-lib/core	83.98% <ø> (ø)

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[aws-cdk-automation]

AWS CodeBuild CI Report

• CodeBuild project: AutoBuildv2Project1C6BFA3F-wQm2hXv2jqQv
• Commit ID: a847497
• Result: SUCCEEDED
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[shikha372]

Thanks @Tietew , there are unit tests that we can update for this change
https://github.com/Tietew/aws-cdk/blob/main/packages/aws-cdk-lib/aws-rds/test/cluster-engine.test.ts#L51
https://github.com/Tietew/aws-cdk/blob/main/packages/aws-cdk-lib/aws-rds/test/cluster-engine.test.ts#L170