Add github actions to dependabot, auto merge on green for dependabot PRs

Signed-off-by: Juraci Paixão Kröhling <juraci@kroehling.de>

.github/dependabot.yml

@@ -4,3 +4,8 @@ updates:
     directory: "/"
     schedule:
       interval: daily
+
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    schedule:
+      interval: "daily"

.github/mergify.yml

@@ -70,3 +70,23 @@ pull_request_rules:
         users:
           - objectiser
           - jpkrohling
+
+  - name: automatic merge for dependabot pull requests
+    conditions:
+      - author~=^dependabot(|-preview)\[bot\]$
+      - "status-success=basic-checks"
+      - "status-success=end-to-end (smoke)"
+      - "status-success=end-to-end (es)"
+      - "status-success=end-to-end (cassandra)"
+      - "status-success=end-to-end (streaming)"
+      - "status-success=end-to-end (examples1)"
+      - "status-success=end-to-end (examples2)"
+      - "status-success=end-to-end (generate)"
+      - "status-success=end-to-end (es-otel)"
+      - "status-success=end-to-end (streaming-otel)"
+      - "status-success=DCO"
+      - "status-success=WIP"
+    actions:
+      merge:
+        method: squash
+        commit_message: title+body