.rultor.yml in rumble-0.6.0 vs .rultor.yml in rumble-0.7.0

@@ -1,14 +1,17 @@
+docker:
+  image: yegor256/rultor-image:1.9.0
 assets:
   rubygems.yml: yegor256/home#assets/rubygems.yml
 install: |
   pdd -f /dev/null
   sudo bundle install --no-color "--gemfile=$(pwd)/Gemfile"
 release:
   script: |-
+    [[ "${tag}" =~ ^[0-9]+\.[0-9]+\.[0-9]+$ ]] || exit -1
     bundle exec rake
     rm -rf *.gem
-    sed -i "s/1\.0\.snapshot/${tag}/g" lib/rumble/version.rb
+    sed -i "s/0\.0\.0/${tag}/g" lib/rumble/version.rb
     git add lib/rumble/version.rb
     git commit -m "version set to ${tag}"
     gem build rumble.gemspec
     chmod 0600 ../rubygems.yml
     gem push *.gem --config-file ../rubygems.yml