workspace: bump Linux to 5.15.32

Bumps Linux to latest LTS patch release

Change-Id: I40e6c4a7e161915d41a688e00cb4ca98553bf89f
Reviewed-on: https://review.monogon.dev/c/monogon/+/644
Reviewed-by: Mateusz Zalega <mateusz@monogon.tech>
diff --git a/WORKSPACE b/WORKSPACE
index 99d79b6..20eba1a 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -134,7 +134,7 @@
 
 linux_external(
     name = "linux",
-    version = "5.15.2",
+    version = "5.15.32",
 )
 
 load("//third_party/linux-firmware:external.bzl", "linux_firmware_external")