weechat: update wee-slack submodule

diff --git a/weechat/python/wee-slack b/weechat/python/wee-slack
index 08d98a0e963d46816bc2202f9c33e858218e6b3e..4b946d8bfa4173113a2bad0f402ff4fd4490919f 160000 (submodule)
--- a/weechat/python/wee-slack
+++ b/weechat/python/wee-slack
@@ -1 +1 @@
-Subproject commit 08d98a0e963d46816bc2202f9c33e858218e6b3e
+Subproject commit 4b946d8bfa4173113a2bad0f402ff4fd4490919f