Update git submodules

* Update docs/submodules/releng from branch 'master'
  to 219801fef20c8cd1838328bd6a3c557092754a7c
  - Merge "Support CentOS 7 in GoogleStorage Gitlab template"
  - Support CentOS 7 in GoogleStorage Gitlab template

    Add a check for `dnf` to the GoogleStorage gitlab-ci template, falling
    back to `yum` if the command is not available. This should allow the job
    to work on both CentOS 7 and 8.

    Change-Id: I0964c23d799bb394bc331bd740a0d6a1cba74082
    Signed-off-by: Trevor Bramwell <tbramwell@linuxfoundation.org>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index 28a3ae9..219801f 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit 28a3ae9fd59a1a9ad875280f440a73987480a0d9
+Subproject commit 219801fef20c8cd1838328bd6a3c557092754a7c