rec: Fix a typo in the FWCatz regression tests

rec: Fix a typo in the FWCatz regression tests

Observed on GH actions:
```
  test_FWCatz.py:353:
  _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

  self = <test_FWCatz.FWCatzXFRRecursorTest testMethod=testFWCatz>
  expected = {'forward_zones': [{'forwarders': ['1.2.3.4'], 'zone': 'c.'}]}

      def checkForwards(self, expected):
          attempts = 0
          tries = 10
          ex = None
          while attempts < tries:
              try:
                  with open('configs/' + self._confdir + '/catzone.forward.catz.') as file:
                      reality = yaml.safe_load(file);
                      if expected == reality:
                          return
              except Exception as e:
                  ex = e
              attempts = attempts + 1
  >           sleep(0.1)
  E           NameError: name 'sleep' is not defined
```