Add compatibility with latest click

Author: Hugo Osvaldo Barrera

setup.py

@@ -11,7 +11,7 @@
 
 requirements = [
     # https://github.com/mitsuhiko/click/issues/200
-    'click>=5.0,<6.0',
+    'click>=5.0',
     'click-log>=0.3.0, <0.4.0',
 
     # https://github.com/pimutils/vdirsyncer/issues/478

tests/system/cli/test_sync.py

@@ -123,7 +123,10 @@ def test_verbosity(tmpdir, runner):
     runner.write_with_general('')
     result = runner.invoke(['--verbosity=HAHA', 'sync'])
     assert result.exception
-    assert 'invalid value for "--verbosity"' in result.output.lower()
+    assert (
+        'invalid value for "--verbosity"' in result.output.lower()
+        or "invalid value for '--verbosity'" in result.output.lower()
+    )
 
 
 def test_collections_cache_invalidation(tmpdir, runner):