Pin grpc related dependencies

We can't use wide dependencies because otherwise when building the
wheel, the latest version is used, but the generate code should use the
minimum supported version for the generation, not the latest one. See:
https://protobuf.dev/support/cross-version-runtime-guarantee/

Signed-off-by: Leandro Lucarella <[email protected]>

Author: llucax

RELEASE_NOTES.md

@@ -1,17 +1,5 @@
 # Frequenz Common API Release Notes
 
-## Summary
-
-<!-- Here goes a general summary of what this release is about -->
-
-## Upgrading
-
-<!-- Here goes notes on how to upgrade from previous versions, including deprecations and what they should be replaced with -->
-
-## New Features
-
-<!-- Here goes the main new features and examples or instructions on how to use them -->
-
 ## Bug Fixes
 
-<!-- Here goes notable bug fixes that are worth a special mention or explanation -->
+- Fix a dependency issue by pinning the `grpcio` version and related libraries.

pyproject.toml

@@ -6,6 +6,13 @@ requires = [
   "setuptools == 68.1.0",
   "setuptools_scm[toml] == 7.1.0",
   "frequenz-repo-config[api] == 0.9.2",
+  # We need to pin the protobuf, grpcio and  grpcio-tools dependencies to make
+  # sure the code is generated using the minimum supported versions, as older
+  # versions can't work with code that was generated with newer versions.
+  # https://protobuf.dev/support/cross-version-runtime-guarantee/#backwards
+  "protobuf == 4.25.3",
+  "grpcio-tools == 1.51.1",
+  "grpcio == 1.51.1",
 ]
 build-backend = "setuptools.build_meta"
 
@@ -25,7 +32,15 @@ classifiers = [
   "Typing :: Typed",
 ]
 requires-python = ">= 3.11, < 4"
-dependencies = ["grpcio >= 1.51.1, < 2", "protobuf >= 4.25.3, < 6"]
+dependencies = [
+  # We can't widen beyond 6 because of protobuf cross-version runtime guarantees
+  # https://protobuf.dev/support/cross-version-runtime-guarantee/#major
+  "protobuf >= 4.25.3, < 6", # Do not widen beyond 6!
+  # We couldn't find any document with a spec about the cross-version runtime
+  # guarantee for grpcio, so unless we find one in the future, we'll assume
+  # major version jumps are not compatible
+  "grpcio >= 1.51.1, < 2", # Do not widen beyond 2!
+]
 dynamic = ["version"]
 
 [[project.authors]]