Add multi-platform support in Woodpecker CI configuration

- Introduce a matrix for building on both linux/arm64 and linux/amd64 platforms.
- Update image tagging to include platform-specific tags for better versioning.
- Enhance the CI configuration for improved build clarity and organization.

.woodpecker.yml

@@ -2,6 +2,16 @@ when:
   branch: [stage, main]
   event: push
 
+matrix:
+  include:
+    - PLATFORM: linux/arm64
+      TAG: arm
+    - PLATFORM: linux/amd64
+      TAG: amd64
+
+labels:
+  platform: ${PLATFORM}
+
 steps:
   - name: build-and-push
     image: plugins/docker
@@ -10,6 +20,6 @@ steps:
       context: .
       repo: registry:5000/flights
       tags:
-        - "${CI_COMMIT_BRANCH}"
-        - "${CI_COMMIT_SHA:0:8}"
+        - "${CI_COMMIT_BRANCH}-${TAG}"
+        - "${CI_COMMIT_SHA:0:8}-${TAG}"
       insecure: true