deps: fix llhttp version number

It's a bit confusing but I think that we acutally have
llhttp version 6.0.6 in master versus 6.0.4. If I check
out 6.0.4 from the llhttp repo and then generate a
release it is missing changes from what we have in Node.js
Checking out 6.0.6 seems to give the matching release
artifacts.

Signed-off-by: Michael Dawson <mdawson@devrus.com>

PR-URL: #43029
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: Richard Lau <rlau@redhat.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

deps/llhttp/include/llhttp.h

@@ -3,7 +3,7 @@
 
 #define LLHTTP_VERSION_MAJOR 6
 #define LLHTTP_VERSION_MINOR 0
-#define LLHTTP_VERSION_PATCH 4
+#define LLHTTP_VERSION_PATCH 6
 
 #ifndef LLHTTP_STRICT_MODE
 # define LLHTTP_STRICT_MODE 0