fix: remove trailing dashes for multidoc yaml

[theurichde]

Fixes #1330 #1296

Description of the change

While introducing multi document support for JSON and YAML, we introduced trailing dashes for YAMLs, which violates the YAML specification. This change will separate JSON and YAML with \n for JSON and --- for YAML, only if there are multiple documents given. It will not append a new line or dashes for the last document

Benefits

YAML specification is met, linters will be happy.

Possible drawbacks

Applicable issues

• fixes kubeseal appends extra document separator --- when format is YAML #1330 kubeseal adds trailing newline to YAML output #1296

Additional information

[tewfik-ghariani]

Or maybe you could simply add the --- at the beginning of every object for YAML format ^^

[theurichde]

Or maybe you could simply add the --- at the beginning of every object for YAML format ^^

Yeah, sure. That would be the more pragmatic way. I thought of having it clean from the beginning, with only a separator in between. But having just the dashes upfront every document, would be also fine for me.

What do you think @alemorcuq @agarcia-oss @alvneiayu ?

[lindhe]

Having --- at the beginning of every YAML document is considered good practice by the the third party tool yamllint: https://yamllint.readthedocs.io/en/stable/configuration.html#default-configuration

[theurichde]

Let's go the pragmatic way. There is also muuuch less code changes involved.

[theurichde]

I will close this PR in favor of #1335