match bundler in Dockerfile

Author: GrantBirki

spec/acceptance/Dockerfile.entitlements-app

@@ -17,7 +17,7 @@ RUN apt-get update && DEBIAN_FRONTEND=noninteractive apt-get install -y \
     pkg-config
 
 # Install bundler
-RUN gem install bundler -v 2.4.22
+RUN gem install bundler -v 2.5.9
 
 # Bootstrap files and caching for speed
 COPY "vendor/cache/" "/data/entitlements-app/vendor/cache/"