[slf4j-dev] [qos-ch/slf4j] 9752c8: specify jdk8 in travis

[Ceki Gulcu]

  Branch: refs/heads/1.7-maintenance
  Home:   https://github.com/qos-ch/slf4j
  Commit: 9752c892fdf4d9d13ea020ac95fca2284ccbf68e
      https://github.com/qos-ch/slf4j/commit/9752c892fdf4d9d13ea020ac95fca2284ccbf68e
  Author: Ceki Gulcu <ceki at qos.ch>
  Date:   2019-08-10 (Sat, 10 Aug 2019)

  Changed paths:
    M .travis.yml

  Log Message:
  -----------
  specify jdk8 in travis