[gnome-build-meta] Revert ".gitlab-ci.yml: update bst and bst-external"

[Michael Catanzaro <mcatanzaro src gnome org>]

commit 5b7bfa46252308ed3ecabfb5a240f1cd59ef6944
Author: Michael Catanzaro <mcatanzaro igalia com>
Date:   Sat Jun 22 12:45:38 2019 -0500

    Revert ".gitlab-ci.yml: update bst and bst-external"
    
    This reverts commit b4fbfca093ee2c9413cca7d24be19f76d1fd3f16.

 .gitlab-ci.yml | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 4323c00f..d5c08b68 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -6,8 +6,8 @@ variables:
   BST_STRICT: '--no-strict'
   BST_TRACK_TAGS: 'False'
   BST: "bst $BST_STRICT --config build.conf --log-file logs/build.log --colors"
-  BST_SHA: '1.2.7-0-g08d1694545d1d62295c7beba1fea65a21b93a723'
-  BST_EXTERNAL_SHA: '0.14.0-0-g003f1f1e7ead60627ef4242a6d785704ede44358'
+  BST_SHA: '1.2.6-0-gac360dfc481c5435a52e31988cc46106cc26d01c'
+  BST_EXTERNAL_SHA: '0.13.0-0-g6121d1909f80379776e7cff21faaf91adfc779e2'
   FLATPAK_BRANCH: master
 
   # Docker Images