The lexer did not jump to the `heredoc_end`, causing the heredoc end delimiter
to be parsed twice.

Normally the heredocs get flushed when a newline is encountered. But because
the newline is part of the string delimiter, that codepath is not taken.

Fixes [Bug #21758]

https://github.com/ruby/prism/commit/7440eb4b11

Mostly not having to list version-specific excludes when testing against ripper/parse.y

Also don't test new syntax additions against the parser gems. The version support
for them may (or may not) be expanded but we shouldn't bother while the ruby version
hasn't even released yet.
(ruby_parser translation is not versioned, so let as is for now)

I also removed excludes that have since been implemented by parse.y

https://github.com/ruby/prism/commit/e5a0221c37

https://github.com/ruby/prism/commit/b00d098f9a

See https://github.com/ruby/ruby/commit/6d81969b475262aba251e99b518181bdf7c5a523

It leaves the old variant around. RuboCop for examples accesses `Prism::Translation::Parser35`
to test against ruby-head. For now I left these simply as an alias

https://github.com/ruby/prism/commit/d0a823f045

Followup to https://github.com/ruby/prism/pull/2213

Before:
```sh
$ ruby -ve "puts 42.~@"
ruby 3.4.6 (2025-09-16 revision https://github.com/ruby/prism/commit/dbd83256b1) +PRISM [x86_64-linux]
-e:1:in '<main>': undefined method '~@' for an instance of Integer (NoMethodError)
Did you mean?  ~
```

After (matches parse.y):
```sh
$ ./miniruby -ve "puts 42.~@"
ruby 3.5.0dev (2025-10-16T03:40:45Z master https://github.com/ruby/prism/commit/1d95d75c3f) +PRISM [x86_64-linux]
-43
```

https://github.com/ruby/prism/commit/a755bf228f

This one has been on my mind for a while now.

Currently, there are only tests against the latest syntax version.

This changes the snapshot structure as follows:
* Snapshots at their current location are tested against all syntax versions
* Snapshots inside a version folder like "3.3" are tested against all versions starting from that version
* Snapshots inside a version folder like "3.3-4.2" are tested against all versions in the given range.

This makes sure that as new syntax is added, older versions still work as expected.
I also added a few tests for now valid syntax that should be invalid in older versions (and the other way around as well)

These tests run really fast. So even though it does 3x the work for these, I am still able to run the whole test suite in just 11 seconds.

https://github.com/ruby/prism/commit/5191b1aa68

https://bugs.ruby-lang.org/issues/21168#note-5

The added code samples align with `parse.y`, except for `foo(bar baz do end)` which `parse.y` currently rejects but shouldn't.

https://github.com/ruby/prism/commit/3a4e102d80

This was a limitation of parse.y that prism intentionally replicated.

https://github.com/ruby/prism/commit/8fd12d594c

https://github.com/ruby/prism/commit/3f58fa7705