add github actions (#4164)

.ci/get_github_upload_url.sh

@@ -0,0 +1,19 @@
+#!/bin/bash
+# this script is to be used by the ci to fetch the github upload url
+# using curl and jq
+[[ $ref ]] || missing+=" ref"
+[[ $repo ]] || missing+=" repo"
+if [[ $missing ]]; then
+  echo "missing env:$missing" >&2
+  exit 2
+fi
+tag="${ref##*/}"
+api_url="https://api.github.com/repos/$repo/releases/tags/$tag"
+upload_url="$(curl "$api_url" | jq -r '.upload_url')"
+if [[ $upload_url && $upload_url != null ]]; then
+  echo "$upload_url"
+  exit 0
+else
+  echo "failed to fetch upload url from $api_url" >&2
+  exit 1
+fi