Pin Bundler to 2.5.23 in CI pipeline to avoid >=2.6.x git cache bug

Author: johnmccrae

.expeditor/verify.pipeline.yml

@@ -143,9 +143,9 @@ steps:
     - gem install bundler -v 2.5.23
     - gem uninstall bundler -v '!= 2.5.23' -a
     - cp scripts/bk_tests/chef_zero-Gemfile oc-chef-pedant/Gemfile
-    - bundle install --jobs=3 --retry=3 --path=/workdir/vendor/bundle
+    - bundle _2.5.23_ install --jobs=3 --retry=3 --path=/workdir/vendor/bundle
     - cd /workdir/oc-chef-pedant
-    - bundle exec rake chef_zero_spec
+    - bundle _2.5.23_ exec rake chef_zero_spec
   expeditor:
     executor:
       docker:
@@ -164,9 +164,9 @@ steps:
     - gem install bundler -v 2.5.23
     - gem uninstall bundler -v '!= 2.5.23' -a
     - cp scripts/bk_tests/chef_zero-Gemfile oc-chef-pedant/Gemfile
-    - bundle install --jobs=3 --retry=3 --path=/workdir/vendor/bundle
+    - bundle _2.5.23_ install --jobs=3 --retry=3 --path=/workdir/vendor/bundle
     - cd /workdir/oc-chef-pedant
-    - bundle exec rake chef_zero_spec
+    - bundle _2.5.23_ exec rake chef_zero_spec
   expeditor:
     executor:
       docker: