Update HydeSlides plugin version

Resolves `?` key help dialog display and previously uncaught
JavaScript errors on initialization and objects are undefined

diff --git a/presentations/dependencies/plugins b/presentations/dependencies/plugins
index d7db175..2bb50af 160000 (submodule)
--- a/presentations/dependencies/plugins
+++ b/presentations/dependencies/plugins
@@ -1 +1 @@
-Subproject commit d7db1752d6df340a9791383326d7d48df3dd4676
+Subproject commit 2bb50af23188d4523fb9371dbd7140759566c7d2