scripted-diff: Bump copyright of files changed in 2019

-BEGIN VERIFY SCRIPT-
./contrib/devtools/copyright_header.py update ./
-END VERIFY SCRIPT-

test/functional/feature_maxuploadtarget.py

@@ -1,5 +1,5 @@
 #!/usr/bin/env python3
-# Copyright (c) 2015-2018 The Bitcoin Core developers
+# Copyright (c) 2015-2019 The Bitcoin Core developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 """Test behavior of -maxuploadtarget.