Update gh-skills-builder plugin to v1.0.4 and regenerate marketplace.json (#2308)

* chore: update gh-skills-builder to v1.0.2

Co-authored-by: arilivigni <4140343+arilivigni@users.noreply.github.com>

* Update gh-skills-builder to v1.0.3 with new commit sha

Co-authored-by: arilivigni <4140343+arilivigni@users.noreply.github.com>

* Update gh-skills-builder external plugin to v1.0.4

Co-authored-by: arilivigni <4140343+arilivigni@users.noreply.github.com>

* Regenerate marketplace.json with gh-skills-builder v1.0.4

Co-authored-by: arilivigni <4140343+arilivigni@users.noreply.github.com>

* Remove connector-namespaces plugin entry

Removed connector-namespaces plugin entry from marketplace.json.

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: arilivigni <4140343+arilivigni@users.noreply.github.com>
Co-authored-by: Aaron Powell <me@aaron-powell.com>

plugins/external.json

@@ -339,7 +339,7 @@
   {
     "name": "gh-skills-builder",
     "description": "Repo: https://github.com/arilivigni/gh-skills-builder\nThis plugin is for people that want to create a GitHub Skills exercise which are self-paced learning GitHub within GitHub.\nhttps://learn.github.com/skills\nexamples:\nhttps://github.com/skills/agent-orchestration-build-your-ai-dream-team\nhttps://github.com/skills/agentic-workflows-that-read-the-room",
-    "version": "1.0.3",
+    "version": "1.0.4",
     "author": {
       "name": "Ari LiVigni",
       "url": "https://github.com/arilivigni"
@@ -358,8 +358,8 @@
     "source": {
       "source": "github",
       "repo": "arilivigni/gh-skills-builder",
-      "ref": "v1.0.3",
-      "sha": "15c1a097ca554d9497f5722e4afb4661f3b73d2b"
+      "ref": "v1.0.4",
+      "sha": "6ec77a69d7203e5df01fd4caa4745089f6930f5d"
     }
   },
   {