Specify encoding when writing output file to avoid errors when defaul…

[cepera-ang]

…t target encoding doesn't have all characters

Specify encoding when writing output file to avoid errors when default target encoding doesn't have all characters. utf8 seems like the most universal and supported encoding. Otherwise, the cli fails with encoding errors when input file contains unicode text (basically most files nowadays) and the target system has default encoding set to some one-byte charset like cp1252

Checklist:

• [x] Commit Message Formatting: Commit titles and messages follow guidelines in the conventional commits.
• [x] Documentation has been updated, if necessary.
• [x] Examples have been added, if necessary.
• [x] Tests have been added, if necessary.