gnu: python-lazr-delegates: Fix test failure.

* gnu/packages/python-xyz.scm (python-lazr-delegates)[arguments]: Invoke
'nosetests' directly instead of through setup.py.  While at it, respect
'--without-tests'.

gnu/packages/python-xyz.scm

@@ -26082,8 +26082,8 @@ and plain text.")
      '(#:phases
        (modify-phases %standard-phases
          (replace 'check
-           (lambda _
-             (invoke "python" "setup.py" "nosetests"))))))
+           (lambda* (#:key tests? #:allow-other-keys)
+             (when tests? (invoke "nosetests")))))))
     (native-inputs
      (list python-nose))
     (propagated-inputs