Update woodpecker build file to use 'steps' instead of 'pipeline'

.woodpecker/build-docker.yml

@@ -1,7 +1,7 @@
 # https://jpetazzo.github.io/2015/09/03/do-not-use-docker-in-docker-for-ci/
 # https://woodpecker-ci.org/docs/usage/volumes
 
-pipeline:
+steps:
   docker-build-go:
     image: docker
     commands:

.woodpecker/build.yml

@@ -2,7 +2,7 @@
 # volume,  which is mounted in all the containers.  So modifying the filesystem (within the working dir)
 # is persistent between build steps.
 
-pipeline:
+steps:
   lint:
     image: offline-twitter/go
     commands: