Woodpecker CI Develop: Also tag images using commit sha

With the commit sha being present, `tags` now has to be a list instead
of an array, otherwise Woodpecker raises a yaml compiler warning:

yaml: line 17: did not find expected ',' or ']'

.woodpecker/docker-develop-combine.yaml

@@ -15,7 +15,10 @@ steps:
       registry: "git.fluffytail.org"
       image: "pleroma-test/pleroma"
       architectures: [amd64, arm64]
-      tags: [latest, develop]
+      tags:
+        - latest
+        - develop
+        - ${CI_COMMIT_SHA}
       username:
         from_secret: pleroma-ci-user
       password: