Replace GitHub merge queue with Mergify queue for DCO compatibility

Configures Mergify to handle merge queue operations with automatic DCO sign-off, resolving DCO check failures on merge commits. Removes GitHub native merge queue triggers from all workflows.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: dsikka

.github/mergify.yml

@@ -1,4 +1,50 @@
+queue_rules:
+  - name: default
+    merge_method: merge
+    commit_message_template: |
+      {{ title }} (#{{ number }})
+
+      {{ body }}
+
+      Signed-off-by: Mergify <noreply@mergify.com>
+    queue_conditions:
+      - check-success=DCO
+      - check-success=quality-check
+      - check-success=transformers-tests
+      - check-success=base-tests (3.10)
+      - check-success=base-tests (3.13)
+      - check-success=pytorch-tests (3.10)
+      - check-success=pytorch-tests (3.13)
+      - check-success=markdown-link-check
+
 pull_request_rules:
+  - name: Automatically merge when ready
+    conditions:
+      - base=main
+      - label=ready
+      - "#approved-reviews-by>=2"
+      - check-success=DCO
+      - check-success=quality-check
+      - check-success=transformers-tests
+      - check-success=base-tests (3.10)
+      - check-success=base-tests (3.13)
+      - check-success=pytorch-tests (3.10)
+      - check-success=pytorch-tests (3.13)
+      - check-success=markdown-link-check
+      - check-success=ready-label-check
+      - -conflict
+      - -draft
+    actions:
+      queue:
+        name: default
+        commit_message_template: |
+          {{ title }} (#{{ number }})
+
+          {{ body }}
+
+          Signed-off-by: Mergify <noreply@mergify.com>
+
+  - name: label-documentation
   - name: label-documentation
     description: Automatically apply documentation label
     conditions:

.github/workflows/linkcheck.yml

@@ -5,7 +5,6 @@ on:
     branches: [ main, 'release/*' ]
   pull_request:
     branches: [ main, 'release/*' ]
-  merge_group:
 
   # Allows you to run this workflow manually from the Actions tab
   workflow_dispatch:

.github/workflows/quality-check.yaml

@@ -4,7 +4,6 @@ on:
     branches: [ main , 'release/*' ]
   pull_request:
     branches: [ main, 'release/*' ]
-  merge_group:
 
 concurrency:
   group: ${{ github.workflow }}-${{ github.ref }}

.github/workflows/test-check-transformers.yaml

@@ -5,7 +5,6 @@ on:
     types: [ labeled, synchronize ]
   push:
     branches: [ main, 'release/*' ]
-  merge_group:
   workflow_dispatch:
     inputs:
       code_coverage:

.github/workflows/test-check.yaml

@@ -4,7 +4,6 @@ on:
     branches: [ main, 'release/*' ]
   push:
     branches: [ main, 'release/*' ]
-  merge_group:
   workflow_dispatch:
     inputs:
       code_coverage: