Travis seems to be triggered properly, I can see recent builds, e.g. https://travis-ci.org/geany/geany-plugins/jobs/202906210 and https://travis-ci.org/geany/geany/builds/202366300. The last build of this PR ran three days ago: https://travis-ci.org/geany/geany/builds/201830001.
For some reason, the build results are not shown here anymore. I don't see yet why.