[network-manager-sstp] Attempting to fix the build by adding gnutls-devel package.

[Eivind Næss <eivnaes src gnome org>]

commit 9cccc2a1861bf608daae1480becea7de89fd9522
Author: Eivind Næss <eivnaes yahoo com>
Date:   Tue Jun 8 14:20:31 2021 -0700

    Attempting to fix the build by adding gnutls-devel package.

 .gitlab-ci.yml | 1 +
 1 file changed, 1 insertion(+)
---
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 31b3faa..9e47817 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -13,6 +13,7 @@
       gettext-devel
       glib2-devel
       gtk3-devel
+      gnutls-devel
       intltool
       libtool
       libsecret-devel