Better separation of version update suggestions

[mikesaelim]

I was looking at rubysec/bundler-audit for features from the last couple years to steal be inspired by, and I thought rubysec/bundler-audit#327 was a good idea. Sometimes, an advisory suggests multiple possible gem versions to upgrade to, and each of those suggestions uses a comma-separated format. For example, the advisory says

patched_versions:
  - "~> 5.2.6, >= 5.2.6.2"
  - "~> 6.0.4, >= 6.0.4.6"
  - "~> 6.1.4, >= 6.1.4.6"
  - ">= 7.0.2.2"

When we join these together, we also separate them with a comma, and it becomes hard to understand. bundler-audit settled on wrapping each version spec with single quotes, before joining them with a comma as before. So in this example, you'd get

Solution: upgrade to '~> 5.2.6, >= 5.2.6.2', '~> 6.0.4, >= 6.0.4.6', '~> 6.1.4, >= 6.1.4.6', '>= 7.0.2.2'

Should we copy what bundler-audit is doing?