Do not manually update system RubyGems (#6355)

Travis CI ships compatible system RubyGems now:
https://github.com/travis-ci/travis-ci/issues/8969#issuecomment-360288970
> I have repackaged the 2.5.0 archive for Linux to include RubyGems 2.7.4,
> which should have the fix for this issue. Please restart the affected
> jobs, and let us know how they go for you.

diff --git a/.travis.yml b/.travis.yml
index f27be2a39b41e02797cbab396529ee8dfcc5836c..35fc49dde450d7d9ad008826a8b7948a930750b0 100644 (file)
--- a/.travis.yml
+++ b/.travis.yml
@@ -47,7 +47,6 @@ services:
   - redis-server
 
 install:
-  - gem update --system
   - nvm install
   - bundle install --path=vendor/bundle --without development production --retry=3 --jobs=16
   - yarn install