[ci] runs rust-audit when top-level Cargo files change

I figure having the `/` in there doesn't work

Author: wookietreiber

.github/workflows/rust-audit.yml

@@ -6,16 +6,16 @@ on:
   pull_request:
     paths:
       - '.github/workflows/rust-audit.yml'
-      - '**/Cargo.toml'
-      - '**/Cargo.lock'
+      - 'Cargo.toml'
+      - 'Cargo.lock'
   push:
     branches:
       - main
       - wip/next
     paths:
       - '.github/workflows/rust-audit.yml'
-      - '**/Cargo.toml'
-      - '**/Cargo.lock'
+      - 'Cargo.toml'
+      - 'Cargo.lock'
   schedule:
     - cron: '0 6 * * 1'