Fix sitemap generate and upload script (#2310)

The CWD is not in the same directory as the script. Use the script from
the global PATH.

Author: another-rex

docker/cron/generate_sitemap/generate_and_upload.sh

@@ -2,13 +2,15 @@
 
 set -e
 
+SCRIPT_PATH=$(dirname "$(readlink -f "$0")")
+
 SITEMAP_OUTPUT="sitemap_output/"
 OUTPUT_BUCKET="${OUTPUT_GCS_BUCKET:=test-osv-dev-sitemap}"
 BASE_URL_PATH="${BASE_URL:=https://test.osv.dev}"
 
 echo "Begin sitemap generation for $BASE_URL_PATH"
 
-./generate_sitemap.py --base_url $BASE_URL_PATH
+"$SCRIPT_PATH/generate_sitemap.py" --base_url $BASE_URL_PATH
 
 echo "Begin Syncing with cloud to $OUTPUT_BUCKET"