Update .ruby-version.sample

Update .ruby-version.sample

…to match the recommended Ruby version

diff --git a/.ruby-version.sample b/.ruby-version.sample
index 57cf282..37c2961 100644
--- a/.ruby-version.sample
+++ b/.ruby-version.sample
@@ -1 +1 @@
-2.6.5
+2.7.2

GitHub sha: c640eee512a0cc6a7ae16da6f75a0044b22b97df

This commit appears in #13905 which was approved by eviltrout. It was merged by eviltrout.