logrus: remove test for dbg alias in ParseLevel.

logrus_test.go

diff --git a/logrus_test.go b/logrus_test.go
index bf5dd6e..15157d1 100644
--- a/logrus_test.go
+++ b/logrus_test.go
@@ -242,10 +242,6 @@
 	assert.Nil(t, err)
 	assert.Equal(t, DebugLevel, l)
 
-	l, err = ParseLevel("dbg")
-	assert.Nil(t, err)
-	assert.Equal(t, DebugLevel, l)
-
 	l, err = ParseLevel("invalid")
 	assert.Equal(t, "not a valid logrus Level: \"invalid\"", err.Error())
 }