fix: remove unnecessary fields in PATCH

[tensor5]

Elements in the codeHosting array contain fields such as createdAt and updatedAt.

[tensor5]

italia/developers-italia-api#253

[bfabio]

This will turn all codeHostings to group = true when issuing a PATCH request, as it's the default value if group is missing, even if it was previously false (PATCH /publishers documentation).

JSON Merge Patch doesn't deep merge arrays, so the correct way to do it is to resend group as well. I would set group = true for the codeHosting being onboarded as well, for good measure and to be explicit. I can't remember if there are tests in the API checking that a PATCHed Publisher with no group in a codeHosting sets it to true, but it's a good time to make sure.

Using JSON Patch would be nicer and less error prone, but unfortunately it's not yet implemented in the API for Publishers (italia/developers-italia-api#213).