Remove running pip-audit from CI.

pip has had a recent CVE, and as a library (and not
an app) it is difficult to run pip-audit in a way that
has value but is segregated from pip-audit's own deps
such that we don't encounter this kind of false positive.

Author: Julian

noxfile.py

@@ -64,15 +64,6 @@ def tests(session):
         session.run("pytest", *session.posargs, REFERENCING)
 
 
-@session()
-def audit(session):
-    """
-    Audit dependencies for vulnerabilities.
-    """
-    session.install("pip-audit", ROOT)
-    session.run("python", "-m", "pip_audit")
-
-
 @session(tags=["build"])
 def build(session):
     """