Filter warning about gencode version being one version older

Protobuf guarantees 2 consecutive major versions work together, and we
need to do this while transitioning to new major versions, so the
warning is not providing any useful information or anything we can act
on, so it is better to ignore it.

Signed-off-by: Leandro Lucarella <luca-frequenz@llucax.com>

Author: llucax

pyproject.toml

@@ -168,7 +168,18 @@ disable = [
 ]
 
 [tool.pytest.ini_options]
-addopts = "-W=all -Werror -Wdefault::DeprecationWarning -Wdefault::PendingDeprecationWarning -vv"
+addopts = "-vv"
+filterwarnings = [
+  "error",
+  "once::DeprecationWarning",
+  "once::PendingDeprecationWarning",
+  # We ignore warnings about protobuf gencode version being one version older
+  # than the current version, as this is supported by protobuf, and we expect to
+  # have such cases. If we go too far, we will get a proper error anyways.
+  # We use a raw string (single quotes) to avoid the need to escape special
+  # characters as this is a regex.
+  'ignore:Protobuf gencode version .*exactly one major version older.*:UserWarning',
+]
 testpaths = ["pytests"]
 
 [tool.mypy]