update appveyor.yml

 * Visual Studio 2019 image is specified
 * Branch "incoming" is added
 * Not to use customized Gemfile
 * Not to build and install gem but only to execute rake normally
 * Update ruby versions
 * Add installation retry and caching, copied from jekyll repository
 * References:
   * https://www.appveyor.com/docs/lang/ruby/
   * https://github.com/jekyll/jekyll/blob/master/appveyor.yml

appveyor.yml

@@ -1,29 +1,30 @@
 ---
 version: "{build}"
+image: Visual Studio 2019
 branches:
   only:
     - master
+    - incoming
 clone_depth: 10
 install:
   - SET PATH=C:\Ruby%ruby_version%\bin;%PATH%
-  - SET BUNDLE_GEMFILE=gemfiles/Gemfile.windows
-  - bundle install
-  - bundle exec rake regemspec
-  - bundle exec rake gem
-  - bundle exec gem install pkg/bio-*.gem
-  - echo gem "bio" >> gemfiles\Gemfile.windows
+  - bundle config set --local path vendor\bundle
+  - bundle install --retry 5 --jobs=%NUMBER_OF_PROCESSORS%
 build: off
 before_test:
   - ruby --version
   - gem --version
   - bundle --version
 test_script:
-  - bundle exec rake gem-test
+  - bundle exec rake
 environment:
   matrix:
-    - ruby_version: "23"
-    - ruby_version: "23-x64"
-    - ruby_version: "24"
-    - ruby_version: "24-x64"
-    - ruby_version: "25"
-    - ruby_version: "25-x64"
+    - ruby_version: "27"
+    - ruby_version: "27-x64"
+    - ruby_version: "30"
+    - ruby_version: "30-x64"
+    - ruby_version: "31"
+    - ruby_version: "31-x64"
+cache:
+# If one of the files after the right arrow changes, cache will be invalidated
+  - 'vendor\bundle -> appveyor.yml,Gemfile,bioruby.gemspec'