Unicode characters in podcast information can cause OPML export to fail

[Keeper-of-the-Keys]

Discovered today with https://podcast.thelinuxexp.com/@tlenewspodcast

He uses \u2019 for ' in the description.

Caused the following error:

WARNING:gpodder.util:Exception while atomic-saving file: 'ascii' codec can't encode character '\u2019' in position 2086: ordinal not in range(128)
Traceback (most recent call last):
  File "/usr/share/harbour-org.gpodder.sailfish/gpodder/util.py", line 817, in update_file_safely
    yield tmp_filename
  File "/usr/share/harbour-org.gpodder.sailfish/gpodder/opml.py", line 202, in write
    fp.write(doc.toprettyxml(indent='  ', newl=os.linesep))
UnicodeEncodeError: 'ascii' codec can't encode character '\u2019' in position 2086: ordinal not in range(128)
ERROR:gpodder.opml:Could not open file for writing: /home/defaultuser/Documents/test.opml
Traceback (most recent call last):
  File "/usr/share/harbour-org.gpodder.sailfish/gpodder/opml.py", line 202, in write
    fp.write(doc.toprettyxml(indent='  ', newl=os.linesep))
UnicodeEncodeError: 'ascii' codec can't encode character '\u2019' in position 2086: ordinal not in range(128)

Solution is probably to move to utf-8 instead of ascii, not sure if this is an issue in gpodder or the libraries being used, will investigate more.