Update part 3 for most recent model, hardware scales, and same datasets as part 1

...s-hls4ml/L1TMLDemo/L1TMLDemo_v1/L1TMLDemo_emulator_v1.cpp

...mssw/src/L1Trigger/L1TMLDemo/plugins/l1tDemoMLAnalyzer.cc

...cmssw/src/L1Trigger/L1TMLDemo/test/L1TMLDemo_NanoAOD.root

part3/cmssw/src/L1Trigger/L1TMLDemo/test/demoL1TMLNtuple.py

...3/cmssw/src/L1Trigger/L1TMLDemo/test/demoL1TMLNtuple.root

...3/cmssw/src/L1Trigger/L1TMLDemo/test/files_background.txt

part3/cmssw/src/L1Trigger/L1TMLDemo/test/files_signal.txt

part3/exercise.md

part3/part3.ipynb