[emacs] remove slack and most of its deps

[~bandali/configs] / lib / slack

diff --git a/lib/slack b/lib/slack
deleted file mode 160000 (submodule)
index 3f76747..0000000
--- a/lib/slack
+++ /dev/null
@@ -1 +0,0 @@
-Subproject commit 3f76747d7424b0746b5397aab5c9ab5a79bba470