Move test_old_deps.sh to new ci dir

.github/workflows/tests.yml

@@ -144,7 +144,7 @@ jobs:
         uses: docker://ubuntu:bionic # For old python and sqlite
         with:
           workdir: /github/workspace
-          entrypoint: .buildkite/scripts/test_old_deps.sh
+          entrypoint: ci/scripts/test_old_deps.sh
         env:
           TRIAL_FLAGS: "--jobs=2"
       - name: Dump logs

MANIFEST.in

@@ -47,6 +47,7 @@ recursive-include changelog.d *
 prune .buildkite
 prune .circleci
 prune .github
+prune ci
 prune contrib
 prune debian
 prune demo/etc

.buildkite/scripts/test_old_deps.sh → ci/scripts/test_old_deps.sh

 #!/usr/bin/env bash
 
-# this script is run by buildkite in a plain `bionic` container; it installs the
+# this script is run by GitHub Actions in a plain `bionic` container; it installs the
 # minimal requirements for tox and hands over to the py3-old tox environment.
 
 set -ex