feat: Restrict the CI to Go files

.woodpecker.yml

@@ -1,11 +1,20 @@
+x-anchors:
+  golang_filter: &golang_filter
+    - path:
+      include: [ "**/*.go" ]
+
 steps:
   build:
     image: "golang:1.21.5-alpine"
     commands:
       - go build ./cmd/rio
       - go test $(go list ./... | grep -v /vendor/)
+    when:
+      - <<: *golang_filter
   lint:
     image: "golang:1.21.5-alpine"
     commands:
       - go fmt $(go list ./... | grep -v /vendor/)
-      - go vet $(go list ./... | grep -v /vendor/)
+      - go vet $(go list ./... | grep -v /vendor/)
+    when:
+      - <<: *golang_filter