feat: audit checks in main CI

Signed-off-by: Christina Sørensen <ces@fem.gg>

.github/workflows/unit-tests.yml

@@ -14,6 +14,13 @@ env:
   CARGO_TERM_COLOR: always
   RUSTFLAGS: --deny warnings
 jobs:
+  security_audit:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: taiki-e/install-action@cargo-deny
+      - name: Scan for vulnerabilities
+        run: cargo deny check
   check_if_pr:
     runs-on: ubuntu-latest
     outputs: