chore: bump node version for gitpod dev container (#16691)

This PR bumps the node version from v10 to v12 for the gitpod dev container using `jsii/superchain`.

Fixes: #16690 

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

.gitpod.yml

@@ -3,11 +3,11 @@ github:
     pullRequestsFromForks: true
     addComment: true
 
-image: jsii/superchain
+image: jsii/superchain:1-buster-slim
 
 tasks:
   - init: yarn build --skip-test --no-bail --skip-prereqs --skip-compat
 
 vscode:
   extensions:
-    - [email protected].5:9Wg0Glx/TwD8ElFBg+FKcQ==
+    - [email protected].20