chore(ci): run notifications also from PRs merged from forks

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>

.github/workflows/notify-models.yaml

@@ -1,9 +1,13 @@
 name: Notifications for new models
 on:
-  pull_request:
+  pull_request_target:
      types:
        - closed
 
+permissions:
+  contents: read
+  pull-requests: read
+
 jobs:
   notify-discord:
     if: ${{ (github.event.pull_request.merged == true) && (contains(github.event.pull_request.labels.*.name, 'area/ai-model')) }}
@@ -12,7 +16,7 @@ jobs:
     - uses: actions/checkout@v5
       with:
         fetch-depth: 0 # needed to checkout all branches for this Action to work
-        # Check the PR diff using the current branch and the base branch of the PR
+        ref: ${{ github.event.pull_request.head.sha }} # Checkout the PR head to get the actual changes
     - uses: GrantBirki/git-diff-action@v2.8.1
       id: git-diff-action
       with:
@@ -85,7 +89,7 @@ jobs:
     - uses: actions/checkout@v5
       with:
         fetch-depth: 0 # needed to checkout all branches for this Action to work
-      # Check the PR diff using the current branch and the base branch of the PR
+        ref: ${{ github.event.pull_request.head.sha }} # Checkout the PR head to get the actual changes
     - uses: GrantBirki/git-diff-action@v2.8.1
       id: git-diff-action
       with: