try something more direct

.woodpecker.yml

@@ -1,4 +1,13 @@
 pipeline:
+  test:
+    image: debian:stable
+    secrets: [ ssh_key ]
+    environment:
+      - ANSIBLE_PRIVATE_KEY=$SSH_KEY
+    commands:
+      - apt-get update && apt-get install ansible -y
+      - ansible-playbook --user igor --inventory hosts.ini main.yml
+
   publish:
     image: plugins/ansible
     pull: true