debian: add workaroud for pyproj

debian: add workaroud for pyproj

Running panikdb-manage from some unreadable directories will fail
with pyproj trying to open some file from it. Change current directory
to / if current directory is not readable as pyproj doesn't exhibit
this behaviour for /.

  File "/usr/lib/python3/dist-packages/combo/apps/maps/models.py", line 20, in <module>
    import pyproj
  File "/usr/lib/python3/dist-packages/pyproj/__init__.py", line 76, in <module>
    _pyproj_global_context_initialize()
  File "pyproj/_datadir.pyx", line 183, in pyproj._datadir._pyproj_global_context_initialize
  File "pyproj/_datadir.pyx", line 132, in pyproj._datadir.pyproj_context_initialize
  File "pyproj/_datadir.pyx", line 105, in pyproj._datadir.set_context_data_dir
  File "/usr/lib/python3/dist-packages/pyproj/datadir.py", line 97, in get_data_dir
    elif valid_data_dirs(proj_lib_dirs):
  File "/usr/lib/python3/dist-packages/pyproj/datadir.py", line 89, in valid_data_dirs
    if valid_data_dir(proj_data_dir):
  File "/usr/lib/python3/dist-packages/pyproj/datadir.py", line 80, in valid_data_dir
    and Path(potential_data_dir, "proj.db").exists()
  File "/usr/lib/python3.9/pathlib.py", line 1407, in exists
    self.stat()
  File "/usr/lib/python3.9/pathlib.py", line 1221, in stat
    return self._accessor.stat(self)
PermissionError: [Errno 13] Permission denied: 'proj.db'