rust/pv_core: Remove mockito dependency

With f6c6f0cc71 ("rust/pv/test: Code + Certificate refactoring")
no code uses mockito anymore, but it's dependency was not removed.

Remove the mockito dependency from the rust workspace.

Signed-off-by: Steffen Eiden <seiden@linux.ibm.com>

rust/pv_core/Cargo.toml

@@ -17,5 +17,3 @@ byteorder = "1.3"
 
 [dev-dependencies]
 serde_test = "1"
-mockito = {version = "1", default-features = false }
-lazy_static = "1.1"