.travis.yml in cose-0.5.0 vs .travis.yml in cose-0.6.0

@@ -2,18 +2,27 @@
 language: ruby
 
 rvm:
   - ruby-head
   - 2.6.2
-  - 2.5.4
-  - 2.4.5
+  - 2.5.5
+  - 2.4.6
+  - 2.3.8
+  - 2.2.10
 
 gemfile:
   - gemfiles/openssl_2_0.gemfile
   - gemfiles/openssl_2_1.gemfile
+  - gemfiles/openssl_default.gemfile
 
-before_install: gem install bundler -v 2.0.1
+before_install: gem install bundler -v '~> 1.17'
 
 matrix:
   fast_finish: true
   allow_failures:
     - rvm: ruby-head
+    - rvm: 2.2.10
+  exclude:
+    - rvm: 2.2.10
+      gemfile: gemfiles/openssl_2_0.gemfile
+    - rvm: 2.2.10
+      gemfile: gemfiles/openssl_2_1.gemfile