chore: config backport to support ts5.5 release (backport #1256) (#1274)

# Backport

This will backport the following commits from `main` to
`maintenance/v5.3`:
- [feat: TypeScript 5.5
(#1256)](#1256)

<!--- Backport version: 9.5.1 -->

### Questions ?
Please refer to the [Backport tool
documentation](https://github.com/sorenlouv/backport)

---------

Co-authored-by: mikewrighton <[email protected]>
Co-authored-by: Momo Kornher <[email protected]>

.projenrc.ts

@@ -6,20 +6,24 @@ import { SUPPORT_POLICY, SupportPolicy } from './projenrc/support';
 import { UpdateIntegPackage } from './projenrc/update-integ-package';
 import { UpgradeDependencies } from './projenrc/upgrade-dependencies';
 
-// See 'projenrc/support.ts' for TypeScript versions we are tracking. To add a new version:
+//  See 'projenrc/support.ts' for TypeScript versions we are tracking. To add a new version:
 //
-// 1. Fork the current `main` to a maintenance branch:
-//    `git push origin main:maintenance/vx.y` (x.y is the TS version that is about to be replaced by a new release)
-// 2. Add a branch protection rule for the new maintenance branch
-// 3. Edit `support.ts`, maintenance EOL date for the current version is 6 months from
-//    today, make the new version current.
-// 4. Update `minNodeVersion` to the oldest LTS version of Node (i.e. dropping support for EOL versions of Node)
-// 5. `npx projen`
-// 6. Update the version list in the README (remember to remove EOS versions)
-// 7. Create a PR
-// 8. Note that merging the PR doesn't trigger a release. Release are perfoemd on a weekly schedule, you should manully create a release by trigeeting this workflow:
-//    https://github.com/aws/jsii-compiler/actions/workflows/auto-tag-releases.yml
-// 9. Perform new version steps for `jsii-rosetta`
+//  1. Fork the current `main` to a maintenance branch:
+//     `git switch main && git fetch --all && git pull`
+//     `git push origin main:maintenance/vX.Y` (X.Y is the TS version that is about to be replaced by a new release)
+//  2. Add a branch protection rule for the new maintenance branch.
+//     Copy the settings from the branch for the version that is about to be replaced.
+//  3. Edit `projenrc/support.ts`, maintenance EOL date for the current version to be 6 months from
+//     today (round up to the mid-point or end of month), make the new version current.
+//  4. Update `minNodeVersion` to the oldest LTS version of Node (i.e. dropping support for EOL versions of Node)
+//  5. `npx projen`
+//  6. Update the version list in the README (remember to remove EOS versions)
+//  7. If any versions dropped into EOS, change the respective branch protection rule to include "Lock branch"
+//  8. Create a PR, with title "eat: TypeScript X.Y"
+//  9. Note that merging the PR doesn't trigger a release. Release are performed on a weekly schedule.
+//     You need to manually create a release by triggering this workflow:
+//     https://github.com/aws/jsii-compiler/actions/workflows/auto-tag-releases.yml
+// 10. Perform new version steps for `jsii-rosetta`
 
 const project = new typescript.TypeScriptProject({
   projenrcTs: true,

projenrc/support.ts

@@ -9,6 +9,7 @@ export const SUPPORT_POLICY: ReleasesDocument = {
     '5.1': new Date('2024-02-28'),
     '5.2': new Date('2024-06-30'),
     '5.3': new Date('2024-10-15'),
+    '5.4': new Date('2025-02-28'),
   },
 };