[hailtop] Use python3.8-compatible format string for json logger (#11839)
[hailtop] Use python3.8-compatible format string for json logger (#11839)


hail-is/hail,hail-is/hail,hail-is/hail,hail-is/hail,hail-is/hail,hail-is/hail,hail-is/hail,hail-is/hail