Remove stale v0.67.2 from actions-lock, restore checkout github-app auth

The checkout of microsoft/aspire.dev requires a GitHub App token
because the microsoft org enforces authentication in Actions. Restore
the github-app block on the checkout section.

Also remove the invalid 'permission-discussions: write' lines from
the compiled lock file (gh aw compiler bug - discussions is not a
valid GitHub Apps API permission scope).

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: IEvangelist

.github/aw/actions-lock.json

@@ -9,11 +9,6 @@
       "repo": "github/gh-aw-actions/setup",
       "version": "v0.67.1",
       "sha": "80471a493be8c528dd27daf73cd644242a7965e0"
-    },
-    "github/gh-aw-actions/setup@v0.67.2": {
-      "repo": "github/gh-aw-actions/setup",
-      "version": "v0.67.2",
-      "sha": "03e31e064a68e8d5ad890c92f303cfb5a3536006"
     }
   }
 }

.github/workflows/pr-docs-check.lock.yml

@@ -26,6 +26,11 @@ if: >-
 
 checkout:
   - repository: microsoft/aspire.dev
+    github-app:
+      app-id: ${{ secrets.ASPIRE_BOT_APP_ID }}
+      private-key: ${{ secrets.ASPIRE_BOT_PRIVATE_KEY }}
+      owner: "microsoft"
+      repositories: ["aspire.dev"]
     current: true
 
 permissions: