add encoding explicitly to all calls to open

[HDembinski]

Closes #406

My auto-formatter introduced some format changes. If you don't want this, please set up pre-commit to apply your own autoformatter, see #408

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[HDembinski]

This is absurd. I never signed such nonsense when I contributed to larger OSS projects than this. You automatically have these rights as per your OSS license.

[VikParuchuri]

As per my comment on the issue, I'm closing this. Thanks for the PR