[Buildkite] Enable automatic retries for failed github artifact step (#658)

* [Buildkite] Enable automatic retries for failed github artifact step

This is to handle failures which may occur when attempting to upload assets, per: https://buildkite.com/authelia/authelia/builds/465#537f931f-efc3-4f7b-9527-c927c1425a52.

* [Buildkite] Ensure GitHub artifact step is reported as a failure

When the initial command fails and we remove the release, we need to ensure that the exit status is reported as non-zero to trigger the automatic retry.

.buildkite/deployment.yml

@@ -15,6 +15,8 @@ steps:
 
   - label: ":github: Deploy Artifacts"
     command: ".buildkite/steps/ghartifacts.sh"
+    retry:
+      automatic: true
     agents:
       upload: "fast"
     key: "artifacts"

.buildkite/steps/ghartifacts.sh

@@ -13,4 +13,4 @@ done
 
 echo "--- :github: Deploy artifacts for release: ${BUILDKITE_TAG}"
 git fetch
-hub release create "${BUILDKITE_TAG}" "${artifacts[@]}" -F <(echo -e "${BUILDKITE_TAG}\n\n## Changelog\n$(git log --oneline --pretty='* %h %s' $(git describe --abbrev=0 --tags $(git rev-list --tags --skip=1 --max-count=1))...$(git describe --abbrev=0 --tags))\n\n## Docker Container\n* \`docker pull authelia/authelia:${BUILDKITE_TAG//v}\`")
+hub release create "${BUILDKITE_TAG}" "${artifacts[@]}" -F <(echo -e "${BUILDKITE_TAG}\n\n## Changelog\n$(git log --oneline --pretty='* %h %s' $(git describe --abbrev=0 --tags $(git rev-list --tags --skip=1 --max-count=1))...$(git describe --abbrev=0 --tags))\n\n## Docker Container\n* \`docker pull authelia/authelia:${BUILDKITE_TAG//v}\`") || hub release delete "${BUILDKITE_TAG}" && false