Move to 1.13.0-SNAPSHOT

[Fokko]

Now 1.12.0 has been released 🥳

What is the purpose of the change

(For example: This pull request improves file read performance by buffering data, fixing AVRO-XXXX.)

Verifying this change

(Please pick one of the following options)

This change is a trivial rework / code cleanup without any test coverage.

(or)

This change is already covered by existing tests, such as (please describe tests).

(or)

This change added tests and can be verified as follows:

(example:)

• Extended interop tests to verify consistent valid schema names between SDKs
• Added test that validates that Java throws an AvroRuntimeException on invalid binary data
• Manually verified the change by building the website and checking the new redirect

Documentation

• Does this pull request introduce a new feature? (yes / no)
• If yes, how is the feature documented? (not applicable / docs / JavaDocs / not documented)

[martin-g]

Most of the other projects use the contents of .../share/VERSION.txt but only the JS SDK does not! Let's also touch lang/js/package.json

[martin-g]

The Java build fails with the same symptoms as the problems with the Docker based testing for the 1.12.0 release - https://github.com/apache/avro/actions/runs/10302739342/job/28517089604?pr=3076
The Maven archetype does not see the 1.13.0-SNAPSHOT artifacts in the reactoer build.

[Fokko]

@martin-g The package.json is already updated: https://github.com/apache/avro/pull/3076/files#diff-4390897d44bcb4480050fea93917b5f82e63877c33832bfd3262528ab4f761b6R3

[Fokko]

It looks like there are nightly builds available:

But this looks like a chicken and egg situation :/

[Fokko]

Just giving this a try, when it works I'll come up with a cleaner solution