[misc] update ES test from 23.06 to 23.07

Author: rusher

.travis.yml

@@ -68,8 +68,8 @@ jobs:
  - env: srv=mariadb-es v=10.6
  name: "ES 10.6"
  if: type = push AND fork = false
- - env: srv=mariadb-es-test v=23.06
- name: "ES 23.06"
+ - env: srv=mariadb-es-test v=23.07
+ name: "ES 23.07"
  if: type = push AND fork = false
  - env: srv=maxscale
  name: "Maxscale"