Update libocpp to v0.18.0 (#930)

This includes fixes for selectable units for smart charging composite schedules and configurable default limits

Signed-off-by: Kai-Uwe Hermann <[email protected]>

dependencies.yaml

@@ -60,7 +60,7 @@ libevse-security:
 # OCPP
 libocpp:
   git: https://github.com/EVerest/libocpp.git
-  git_tag: c6a6e01b27c994f170d2b21d2befa13ad5c9ca20
+  git_tag: v0.18.0
   cmake_condition: "EVEREST_DEPENDENCY_ENABLED_LIBOCPP"
 # Josev
 Josev: