Fixed buildkite error

Signed-off-by: Kapil Chouhan <kapil.chouhan@msystechnologies.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/Gemfile b/Gemfile
index 37987d8..bd6764e 100644
--- a/Gemfile
+++ b/Gemfile
@@ -2,6 +2,8 @@ source "https://rubygems.org"
 
 gemspec name: "mixlib-shellout"
 
+gem "parallel", "< 1.20" # pin until we drop ruby < 2.4
+
 group :docs do
   gem "yard"
   gem "redcarpet"