build: Fix vm-memory bump build error

A new version of vm-memory was released upstream which resulted in some
components pulling in that new version. Update the version number used
to point to the latest version but continue to use our patched version
due to the fix for #1258

Signed-off-by: Rob Bradford <robert.bradford@intel.com>

vm-allocator/Cargo.toml

@@ -6,5 +6,5 @@ edition = "2018"
 
 [dependencies]
 libc = "0.2.78"
-vm-memory = "0.2.1"
+vm-memory = "0.3.0"
 arch = { path = "../arch" }