[3rdparty] Bump symfony dependencies to 4.2.7

Signed-off-by: Roeland Jago Douma <roeland@famdouma.nl>

diff --git a/3rdparty b/3rdparty
index 4d07f304072e792a88b2cee6ca46af9f0877a76c..9e49623fa57786c0874529e66c2ebd0ff2dc5075 160000 (submodule)
--- a/3rdparty
+++ b/3rdparty
@@ -1 +1 @@
-Subproject commit 4d07f304072e792a88b2cee6ca46af9f0877a76c
+Subproject commit 9e49623fa57786c0874529e66c2ebd0ff2dc5075