fix(deps): relax protobuf constraint to <7.0.0 for opentelemetry compatibility (#3971)

[mrveiss]

Problem: Protobuf constraint was too narrow (>=5.29.6,<6.0.0), preventing pip from resolving dependencies that require protobuf 6.x.

Root cause: TensorFlow 2.19.1 was cited as requiring <6.0.0, but TensorFlow is not actually a project dependency. Meanwhile, opentelemetry-proto>=1.40.0 (a real transitive dependency) explicitly declares protobuf<7.0,>=5.0, which includes protobuf 6.x.

Solution: Relax the upper bound to <7.0.0 to:

• Allow protobuf 6.x which is fully compatible with all dependencies
• Align with opentelemetry-proto's actual constraint
• Prevent pip conflicts on fresh installs

Testing:

• Current installed version: 6.33.6
• All imports verified working: chromadb, opentelemetry.proto, onnxruntime
• No breaking changes

Closes #3971