remove py23 support

Script/CastorScript.py

Script/cs/StorageBackends/castorstorage.py

Script/cs/StorageBackends/eosstorage.py

Script/cs/StorageBackends/storagetester.py

Script/cs/Threads/CopyThread.py

Script/cs/Threads/DdmMonitoringThread.py

Script/cs/Threads/DeleteThread.py

Script/cs/Threads/InfoServiceThread.py

Script/cs/Threads/ManagerThread.py

Script/cs/Threads/ProfiledThread.py

Script/cs/Tools/ConfigParser.py

Script/cs/Tools/FilenameParsers/BCMFileNameParser.py

Script/cs/Tools/FilenameParsers/BCMSimpleFileNameParser.py

Script/cs/Tools/FilenameParsers/BaseFileNameParser.py

Script/cs/Tools/FilenameParsers/BeastFileNameParser.py

Script/cs/Tools/FilenameParsers/CocaFileNameParser.py

Script/cs/Tools/FilenameParsers/MUCalibNameParser.py

Script/cs/Tools/FilenameParsers/SCTFileNameParser.py

Script/cs/Tools/FilenameParsers/SFOFileNameParser.py

Script/cs/Tools/Libraries/Database.py