Add woodpecker pipeline

.woodpecker/build.yml

@@ -0,0 +1,25 @@
+when:
+  - event: push
+
+steps:
+  - name: build
+    image: eclipse-temurin:21-jdk-alpine
+    commands:
+      - ./mvnw clean package
+
+  - name: notify
+    image: deblan/woodpecker-email
+    settings:
+      debug: true
+      dsn:
+        from_secret: smtp_url
+      from:
+        address:
+          from_secret: email_sender
+        name: "Woodpecker CI"
+      recipients_only: true
+      recipients:
+        from_secret: email_recipient
+    when:
+      status:
+        - failure