fix: change protoc version to v29.5 and protobuf to >=5 (#141)

Generate code with protoc 29.5 which allows to run the code with 
any version of the protobuf library that's newer than v5.x.

Signed-off-by: Niels Pardon <par@zurich.ibm.com>

Author: nielspardon

buf.gen.yaml

@@ -1,6 +1,6 @@
 version: v2
 plugins:
-  - remote: buf.build/protocolbuffers/python:v33.2
+  - remote: buf.build/protocolbuffers/python:v29.5
     out: src
-  - remote: buf.build/community/nipunn1313-mypy:v4.0.0
+  - remote: buf.build/community/nipunn1313-mypy:v3.7.0
     out: src

pixi.lock

@@ -5,7 +5,7 @@ authors = [{name = "Substrait contributors", email = "substrait@googlegroups.com
 license = {text = "Apache-2.0"}
 readme = "README.md"
 requires-python = ">=3.10,<3.14"
-dependencies = ["protobuf >=6.33,<7"]
+dependencies = ["protobuf >=5,<7"]
 dynamic = ["version"]
 
 [tool.setuptools_scm]