Add in-tree buildkite pipeline

ci/publish.sh

@@ -0,0 +1,19 @@
+#!/bin/bash -e
+
+cd $(dirname $0)/..
+
+if [[ -z "$BUILDKITE_TAG" ]]; then
+  # Skip publish if this is not a tagged release
+  exit 0
+fi
+
+if [[ -z "$CRATES_IO_TOKEN" ]];
+  echo CRATES_IO_TOKEN undefined
+  exit 1
+fi
+
+cargo package
+# TODO: Ensure the published version matches the contents of BUILDKITE_TAG
+cargo publish --token "$CRATES_IO_TOKEN"
+
+exit 0