Delete pipeline-simple.yml; it's old

This pipeline's only purpose was an asset in a blog post that I wrote a
couple of years ago, and is no longer necessary.

Also, and this sounds petty, but I didn't like the RED on my CI--I'd
like to see as much green as possible. Now my CI is green (with the
exception of the many-colored "badges" pipeline).

ci/pipeline-simple.yml

@@ -1,39 +0,0 @@
-# fly -t nono sp -p simple -c pipeline-simple.yml
-# fly -t nono expose-pipeline -p simple
-# fly -t nono unpause-pipeline -p simple
-jobs:
-- name: unit
-  plan:
-  - get: src
-    trigger: true
-  - task: unit
-    config:
-      platform: linux
-      image_resource:
-        type: docker-image
-        source:
-          repository: fedora
-      run:
-        path: "true"
-
-- name: integration
-  plan:
-  - get: src
-    trigger: true
-    passed: [unit]
-  - task: integration
-    config:
-      platform: linux
-      image_resource:
-        type: docker-image
-        source:
-          repository: fedora
-      run:
-        path: "false"
-
-resources:
-- name: src
-  type: git
-  icon: github
-  source:
-    uri: https://github.com/cunnie/sslip.io