psych quoting strings if they begin with dash.

Strings are quoted if they begin with a dash. This is causing issues for an external parser I'm forced to use and inquiring because of the difference in behaviour with python's yaml module.

irb(main):001:0> require 'yaml'
=> true
irb(main):002:0> puts YAML.dump({'key' => 'value' })
---
key: value
=> nil
irb(main):003:0> puts YAML.dump({'key' => '-value' })
---
key: "-value"
=> nil
irb(main):004:0> puts YAML.dump({'-key' => '-value' })
---
"-key": "-value"
=> nil

Compared to python

>>> import yaml
>>> print(yaml.dump({'key': 'value'}))
key: value

>>> print(yaml.dump({'key': '-value'}))
key: -value

>>> print(yaml.dump({'-key': '-value'}))
-key: -value

Start by reproducing the YAML.dump examples from the issue and inspect Psych's scalar and mapping-key emission path. Done means dash-leading string values and keys serialize without unnecessary quotes while remaining valid YAML and preserving existing safety behavior.