add dependencies for GCompris website

Qt5 tools for lconvert and lrelease htmlmin, PyQt5 and Jinja2 as python dependencies

I've installed PyQt5==5.12 because with the latest (5.15.9), the following error appeared:

14.84 Collecting PyQt5
14.88   Downloading PyQt5-5.15.9.tar.gz (3.2 MB)
16.03   Installing build dependencies: started
21.60   Installing build dependencies: finished with status 'done'
21.60   Getting requirements to build wheel: started
21.84   Getting requirements to build wheel: finished with status 'done'
21.84     Preparing wheel metadata: started
22.12     Preparing wheel metadata: finished with status 'error'
22.12     ERROR: Command errored out with exit status 1:
22.12      command: /usr/bin/python3 /tmp/tmpphzmnbwy prepare_metadata_for_build_wheel /tmp/tmp2_nld0z7
22.12          cwd: /tmp/pip-install-saqgcx6a/PyQt5
22.12     Complete output (36 lines):
22.12     Querying qmake about your Qt installation...
22.12     Traceback (most recent call last):
22.12       File "/tmp/tmpphzmnbwy", line 126, in prepare_metadata_for_build_wheel
22.12         hook = backend.prepare_metadata_for_build_wheel
22.12     AttributeError: module 'sipbuild.api' has no attribute 'prepare_metadata_for_build_wheel'
22.12
22.12     During handling of the above exception, another exception occurred:
22.12
22.12     Traceback (most recent call last):
22.12       File "/tmp/tmpphzmnbwy", line 280, in <module>
22.12         main()
22.12       File "/tmp/tmpphzmnbwy", line 263, in main
22.12         json_out['return_val'] = hook(**hook_input['kwargs'])
22.12       File "/tmp/tmpphzmnbwy", line 130, in prepare_metadata_for_build_wheel
22.12         return _get_wheel_metadata_from_wheel(backend, metadata_directory,
22.12       File "/tmp/tmpphzmnbwy", line 159, in _get_wheel_metadata_from_wheel
22.12         whl_basename = backend.build_wheel(metadata_directory, config_settings)
22.12       File "/tmp/pip-build-env-064_jrr0/overlay/lib/python3.8/site-packages/sipbuild/api.py", line 46, in build_wheel
22.12         project = AbstractProject.bootstrap('wheel',
22.12       File "/tmp/pip-build-env-064_jrr0/overlay/lib/python3.8/site-packages/sipbuild/abstract_project.py", line 87, in bootstrap
22.12         project.setup(pyproject, tool, tool_description)
22.12       File "/tmp/pip-build-env-064_jrr0/overlay/lib/python3.8/site-packages/sipbuild/project.py", line 586, in setup
22.12         self.apply_user_defaults(tool)
22.12       File "/tmp/pip-install-saqgcx6a/PyQt5/project.py", line 68, in apply_user_defaults
22.12         super().apply_user_defaults(tool)
22.12       File "/tmp/pip-build-env-064_jrr0/overlay/lib/python3.8/site-packages/pyqtbuild/project.py", line 70, in apply_user_defaults
22.12         super().apply_user_defaults(tool)
22.12       File "/tmp/pip-build-env-064_jrr0/overlay/lib/python3.8/site-packages/sipbuild/project.py", line 237, in apply_user_defaults
22.12         self.builder.apply_user_defaults(tool)
22.12       File "/tmp/pip-build-env-064_jrr0/overlay/lib/python3.8/site-packages/pyqtbuild/builder.py", line 78, in apply_user_defaults
22.12         self._get_qt_configuration()
22.12       File "/tmp/pip-build-env-064_jrr0/overlay/lib/python3.8/site-packages/pyqtbuild/builder.py", line 497, in _get_qt_configuration
22.12         for line in project.read_command_pipe([self.qmake, '-query']):
22.12       File "/tmp/pip-build-env-064_jrr0/overlay/lib/python3.8/site-packages/sipbuild/project.py", line 554, in read_command_pipe
22.12         raise UserException(
22.12     sipbuild.exceptions.UserException