Update git submodules

* Update vendor from branch 'REL1_31'
  to a48c47a029213b44e032b8dcdd4795876cfc93a8
  - Switch to our less.php fork

    Bug: T206975
    Change-Id: I01e0b3328c8e1c4a69c37a471e436acd8911f1fa

diff --git a/vendor b/vendor
index 5f60e30..a48c47a 160000 (submodule)
--- a/vendor
+++ b/vendor
@@ -1 +1 @@
-Subproject commit 5f60e30d272ea5327b407e625b4398952d49f8cf
+Subproject commit a48c47a029213b44e032b8dcdd4795876cfc93a8