Set ABI 14 for pypi builds

On publish, the pypi workflow currently regenerates our parser for ABI
15 because that's the default from the central workflow [1].

In Python, one needs py-tree-sitter [2] to load the robot language.
Since py-tree-sitter folks have not yet finished ABI 15 migration,
there's currently no way to load our binding. Using the lattest
py-tree-sitter 0.24 would fail with "ValueError: Incompatible Language
version 15. Must be between 13 and 14".

Therefore to make tree-sitter-robot available for users, we enforce ABI
14 on regeneration for upload.

PS: Some of the central language bindings have basically the same
problem. However, since they have published former pypi releases with
lower ABI versions, there's something users can fallback to. We don't
have previous releases, so no fallback is available.

[1] https://github.com/tree-sitter/workflows/blob/ec44bc4f4667a458dd397ed9864f1b560e8fdca2/.github/workflows/package-pypi.yml#L24
[2] https://github.com/tree-sitter/py-tree-sitter
[3] tree-sitter/py-tree-sitter#333

Author: haxtibal

.github/workflows/publish.yaml

@@ -29,6 +29,7 @@ jobs:
       PYPI_API_TOKEN: ${{secrets.PYPI_API_TOKEN}}
     with:
       generate: true
+      abi-version: 14
 
   # Maybe in the future:
   #