Fix Jenkins builds

Multiple jobs in Jenkins are failing due to different reasons:

•  MAC build is failed - fixed it by constraining jinja2 and flask to compatible versions

  Installed /WORK/anaconda3/anaconda3/envs/mac-distribution/lib/python3.7/site-packages/tvb_build-2.0-py3.7.egg
  Processing dependencies for tvb-build==2.0
  error: Jinja2 3.0.1 is installed but jinja2<2.12.0,>=2.7.3 is required by {'allensdk'}
  

• Windows build is failed - fixed by ignoring the _pycache_ folder at copy time

  Installed c:\jenkins_home\workspace\tvb - build - windows\tvb_build
   Generating ANACONDA-based TVB_Distribution! Windows
   -  Removing old artifacts
   -  Decompressing build\TVB_build_step1.zip into 'build\TVB_Distribution' ...
   -  Copying anaconda ENV folderC:\miniconda\envs\tvb-run into 'build\TVB_Distribution\tvb_data'...
  Traceback (most recent call last):
    File "build_from_conda.py", line 298, in <module>
      prepare_anaconda_dist(Config.win64())
    File "build_from_conda.py", line 259, in prepare_anaconda_dist
      shutil.copytree(config.anaconda_env_path, config.target_library_root)
    File "C:\miniconda\envs\tvb-run\lib\shutil.py", line 368, in copytree
      raise Error(errors)
  shutil.Error: [('C:\\miniconda\\envs\\tvb-run\\Lib\\site-packages\\allensdk\\brain_observatory\\behavior\\data_objects\\metadata\\ophys_experiment_metadata\\multi_plane_metadata\\__pycache__\\
  multi_plane_metadata.cpython-37.pyc', 'build\\TVB_Distribution\\tvb_data\\Lib\\site-packages\\allensdk\\brain_observatory\\behavior\\data_objects\\metadata\\ophys_experiment_metadata\\multi_pl
  ane_metadata\\__pycache__\\multi_plane_metadata.cpython-37.pyc', "[Errno 2] No such file or directory: 'build\\\\TVB_Distribution\\\\tvb_data\\\\Lib\\\\site-packages\\\\allensdk\\\\brain_obser
  vatory\\\\behavior\\\\data_objects\\\\metadata\\\\ophys_experiment_metadata\\\\multi_plane_metadata\\\\__pycache__\\\\multi_plane_metadata.cpython-37.pyc'")]
  

• Test-Sqlite build is running continuously from 5 to 5 minutes being triggered by the TVB-2849 branch that does not exist anymore in Github - fixed it by cleaning the git repo on jenkins machine
• TVB - Step1 fails at coverage step

  tvb/tests/framework/interfaces/neoforms_test.py:44: in <module>
      loader=PackageLoader('tvb.interfaces.web.templates', 'form_fields'),
  /opt/conda/envs/tvb-run/lib/python3.7/site-packages/jinja2/loaders.py:310: in __init__
      f"The {package_name!r} package was not installed in a"
  E   ValueError: The 'tvb.interfaces.web.templates' package was not installed in a way that PackageLoader understands.