appveyor.yml in watir-6.16.5 vs appveyor.yml in watir-6.17.0

- old
+ new

@@ -1,9 +1,10 @@
 version: "#{build}"
 build: off
 clone_depth: 100
 install:
-  - set PATH=C:\Ruby23\bin;%PATH%
+  - set PATH=C:\Ruby25\bin;%PATH%
+  - gem update --system
   - bundle install
 test_script:
   - bundle exec rake %RAKE_TASK%
 environment:
   matrix: