ci: Track build scripts in dependency graph

.deny.toml

@@ -6,12 +6,17 @@ unsound = "deny"
 yanked = "deny"
 notice = "deny"
 git-fetch-with-cli = true
-ignore = []
+ignore = [
+]
 
 # https://embarkstudios.github.io/cargo-deny/checks/bans/cfg.html
 [bans]
 multiple-versions = "warn"
 wildcards = "allow" # https://github.com/EmbarkStudios/cargo-deny/issues/488
+build.allow-build-scripts = [
+    { name = "proc-macro2" },
+    { name = "syn" }, # TODO: update to 2.0
+]
 
 # https://embarkstudios.github.io/cargo-deny/checks/licenses/cfg.html
 [licenses]