Update doesn't respect existing YAML front matter

[hittjwX]

When running python3 sidecar.py --rss-feed https://www.spreaker.com/show/3257924/episodes/feed --directory /workspaces/obsidian/ --update --dry-run --limit 2 the following happens:

• The script removes YAML front matter values that are not in the template. The desired behavior is to respect values that exist beyond the template, even if they are blank.
• Never report a YAML front matter variable with a utm_ prefix. Don't delete anything that is in the front matter beyond the template.
• Don't reformat the tags: values adding quotations. Don't delete any values; only append new values not currently present.
• When writing the title into the front matter, use title case. Clean up the text with title case formatting before updating a missing title: field.
• Only make modifications to documents with type: Podcast where the permalink is an exact match of the RSS episode link value.

[hittjwX]

Improvements were made to the title casing of title and the date format.