Fix spelling of Unknown

Change-Id: I9e8b36a7121abd52dc850bcc78bbda4a7af63727
Reviewed-on: https://review.couchbase.org/c/kv_engine/+/180440
Reviewed-by: James H <james.harrison@couchbase.com>
Tested-by: Trond Norbye <trond.norbye@couchbase.com>

cbsasl/password_database_test.cc

@@ -44,5 +44,5 @@ TEST_F(PasswordDatabaseTest, TestInvalidVersion) {
         EXPECT_STREQ("PasswordDatabase(): Unknown version: 3", e.what());
         failed = true;
     }
-    EXPECT_TRUE(failed) << "Unknonw version should have been detected";
+    EXPECT_TRUE(failed) << "Unknown version should have been detected";
 }