Update configuration for cargo-deny

I've seen warnings about the removal of the key vulnerability for
advisories with the reference to
EmbarkStudios/cargo-deny#611. This indicates
that the default behavior is about to change. Let's switch to the new
defaults now.

deny.toml

@@ -35,12 +35,12 @@ targets = [
 # More documentation for the advisories section can be found here:
 # https://embarkstudios.github.io/cargo-deny/checks/advisories/cfg.html
 [advisories]
+# Selects the default behavior for checking advisories.
+version = 2
 # The path where the advisory database is cloned/fetched into
 db-path = "~/.cargo/advisory-db"
 # The url(s) of the advisory databases to use
 db-urls = ["https://github.com/rustsec/advisory-db"]
-# The lint level for security vulnerabilities
-vulnerability = "deny"
 # The lint level for unmaintained crates
 unmaintained = "deny"
 # The lint level for crates that have been yanked from their source registry
@@ -72,6 +72,8 @@ ignore = [
 # More documentation for the licenses section can be found here:
 # https://embarkstudios.github.io/cargo-deny/checks/licenses/cfg.html
 [licenses]
+# Selects the default behavior for checking licenses.
+version = 2
 # The lint level for crates which do not have a detectable license
 unlicensed = "deny"
 # List of explicitly allowed licenses