Don't install bundler for sequel CI job

Bundler is included in JRuby for a long time now.

Author: headius

tool/sequel-github-actions.sh

@@ -3,7 +3,6 @@ set -v -e
 
 # set up PATH for JRuby
 export PATH=`pwd`/bin:$PATH
-gem install bundler -v "~>1.17.3" --no-document
 
 # set up sequel
 git clone --depth=10 https://github.com/jeremyevans/sequel.git