Use GPS to auto-merge dependabot PRs (dotnet#41879)

Author: gewarren

.github/policies/auto-merge.yml

@@ -8,7 +8,7 @@ where:
 configuration:
   resourceManagementConfiguration:
     eventResponderTasks:
-    - description: Auto-squash-merge PRs to main labeled with auto-merge
+    - description: Approve and auto-squash-merge PRs to main labeled with 'auto-merge'
       triggerOnOwnActions: true
       if:
       - payloadType: Pull_Request
@@ -22,7 +22,7 @@ configuration:
       - approvePullRequest:
           comment: "Approved; this PR will merge when all status checks pass."
 
-    - description: Auto-merge PRs to live labeled with auto-merge
+    - description: Auto-merge PRs to live labeled with 'auto-merge'
       triggerOnOwnActions: true
       if:
       - payloadType: Pull_Request
@@ -34,7 +34,7 @@ configuration:
       - enableAutoMerge:
           mergeMethod: Merge
 
-    - description: Don't auto-merge PRs with auto-merge label removed
+    - description: Don't auto-merge PRs with 'auto-merge' label removed
       if:
       - payloadType: Pull_Request
       - labelRemoved:

.github/policies/label-prs.yml

@@ -60,6 +60,18 @@ configuration:
           - addLabel:
               label: ":octocat: auto-merge"
 
+      - description: Label PRs from dependabot/dependabot[bot]
+        if:
+          - payloadType: Pull_Request
+          - or:
+            - isActivitySender:
+                user: dependabot
+            - isActivitySender:
+                user: dependabot[bot]
+        then:
+          - addLabel:
+              label: ":octocat: auto-merge"
+
       - description: Label PRs with okr-quality
         if:
           - payloadType: Pull_Request