manifest: nanopb: upmerge to version 0.4.6

The upstream version 0.4.6 was tagged. Upmerge the zephyr branch.

Signed-off-by: Pieter De Gendt <pieter.degendt@basalte.be>
diff --git a/west.yml b/west.yml
index 4ccde63..d70123c 100644
--- a/west.yml
+++ b/west.yml
@@ -180,7 +180,7 @@
         - debug
       revision: a5163c1800a5243f8b05d84c942da008df4cb666
     - name: nanopb
-      revision: d148bd26718e4c10414f07a7eb1bd24c62e56c5d
+      revision: dc4deed54fd4c7e1935e3b6387eedf21bb45dc38
       path: modules/lib/nanopb
     - name: net-tools
       revision: e0828aa9629b533644dc96ff6d1295c939bd713c