ci: drop invalid --disable-pip flag from pip-audit

--disable-pip is only valid with -r/--requirement. We audit the
installed environment directly, so the flag is both unnecessary and
rejected by pip-audit's argparse.

Author: kallioli

.github/workflows/ci.yml

@@ -128,4 +128,4 @@ jobs:
           pip install pip-audit
 
       - name: Audit runtime dependencies
-        run: pip-audit --strict --disable-pip
+        run: pip-audit --strict