[plugin][debianqa] fails when .changes file have unicode char in the `Changes` field

While testing debexpo, I've uploaded apache2 (2.4.38-3). The .changes file contains the last entry of the changelog which includes unicode char (è).

Traceback from the importer is:

21:01:09,502 DEBUG [debexpo.plugins.debianqa] Testing whether the package is in Debian already                                                                                    
21:01:09,502 DEBUG [debexpo.plugins.debianqa] Finding when the last upload of the package was                                                                                     
21:01:09,504 WARNI [debexpo.plugins.debianqa] Couldn't find last upload date
21:01:09,504 DEBUG [debexpo.plugins.debianqa] Finding out whether the package is a NMU
21:01:09,510 DEBUG [debexpo.lib.plugins] Something wrong happened while running the plugin 'debianqa': Traceback (most recent call last):                                         
  File "/home/local/workspace/debian/repo/lyknode-guests/debexpo/debexpo/lib/plugins.py", line 232, in _run_plugins                                                               
    result.extend(p.run())
  File "/home/local/workspace/debian/repo/lyknode-guests/debexpo/debexpo/plugins/__init__.py", line 63, in run                                                                    
    getattr(self, method)()
  File "/home/local/workspace/debian/repo/lyknode-guests/debexpo/debexpo/plugins/debianqa.py", line 176, in test_qa                                                               
    self._test_is_nmu()
  File "/home/local/workspace/debian/repo/lyknode-guests/debexpo/debexpo/plugins/debianqa.py", line 114, in _test_is_nmu                                                          
    changes = str(self.changes["Changes"]).lower().translate(None, delete_chars).splitlines()                                                                                     
UnicodeEncodeError: 'ascii' codec can't encode character u'\xe8' in position 338: ordinal not in range(128)

apache2_2.4.38-3_source.changes