Patches have been available (upstream) since this afternoon:
- https://w1.fi/security/2019-1/
- https://w1.fi/security/2019-2/
- https://w1.fi/security/2019-3/
- https://w1.fi/security/2019-4/
OpenWrt fully supports WPA3 in master, but not in 18.06.x or earlier (which doesn't imply that the patches wouldn't be needed there as well).