PD content ingestor adds zero-width spaces

**Describe the bug**

https://github.com/CodeYourFuture/CYF-PD/blob/main/content/blocks/fundamentals-test/readme.md contains a bunch of \uFEFF zero-width non-breaking space characters (e.g. in each "Part 1", "Part 2", etc heading between the "P" and "art") and some \uC2A0 characters.

Not sure why they're there or how they got there, but we should probably remove them, and fix the ingestor to either not add them, or proactively remove them.

It looks like this is maybe caused by https://github.com/decaporg/decap-cms/issues/6602