Unarchive py-ipld-dag and Update Repository Configuration

## Summary

We would like to take on maintenance of the `py-ipld-dag` repository and unarchive it to restore active development.

This is part of the ongoing effort to stabilize and modernize the Python libp2p dependency stack.

I’ve applied configuration defaults based on other active Python repositories in the org. Please let me know if anything should be adjusted.


## Why do you need this?

We are actively maintaining `py-multiaddr`, which depends on `py-cid`, which in turn depends on `py-ipld-dag`.

Although we have access to the PyPI project, the GitHub repository being archived prevents:

* Opening and merging PRs
* Updating CI workflows
* Managing issues
* Coordinating releases across the dependency chain

Unarchiving `py-ipld-dag` is necessary to maintain a clean and sustainable release process for the Python libp2p ecosystem.


## What changes were made?

* Unarchived the repository (`archived: false`)
* Set visibility to `public`
* Configured default branch to `master`
* Enabled `secret_scanning` and `secret_scanning_push_protection`
* Added appropriate team access:

  * `Python Team` (admin)
  * `github-mgmt stewards` (pull)
* Added `web3-bot` with push access
* Updated repository description
* Set repository topics (`cid`, `python`)
* Applied standard merge commit configurations

These reflect defaults used in other maintained Python ecosystem repositories.

---

## What else do we need to know?

DRI: myself

@acul71
@pacrob


## Reviewer’s Checklist

* [ ] It is clear where the request is coming from (if unsure, ask)
* [ ] All the automated checks passed
* [ ] The YAML changes reflect the summary of the request
* [ ] The Terraform plan posted as a comment reflects the summary of the request

Author: seetadev

github/ipld.yml

@@ -1405,7 +1405,31 @@ repositories:
     visibility: public
     web_commit_signoff_required: false
   py-ipld-dag:
-    archived: true
+    advanced_security: false
+    allow_update_branch: false
+    archived: false
+    collaborators:
+      push:
+        - web3-bot
+    default_branch: master
+    description: Python implementation of the CID specification
+    has_discussions: false
+    merge_commit_message: PR_TITLE
+    merge_commit_title: MERGE_MESSAGE
+    secret_scanning_push_protection: true
+    secret_scanning: true
+    squash_merge_commit_message: COMMIT_MESSAGES
+    squash_merge_commit_title: COMMIT_OR_PR_TITLE
+    teams:
+      pull:
+        - github-mgmt stewards
+      push:
+        - Python Team
+    topics:
+      - cid
+      - python
+    visibility: public
+    web_commit_signoff_required: false 
   react-ipld:
     archived: true
   replication: