### Motivation and Context
#8153 bumped the minimum required protobuf version from `4.25.1` to
`6.31.1` in `pyproject.toml`, `pixi.toml`, and `sbom.cdx.json`, but
`workflow_scripts/protobuf/build_protobuf_unix.sh` and
`build_protobuf_win.ps1` were left pinned to the old `protobuf-25.1` /
`abseil-cpp-20230802.2` sources. These scripts are used by `main.yml`,
`lint.yml`, and `win_no_exception_ci.yml` to build protobuf from source
(with `-fPIC` / static runtime) for the C++ test and lint jobs, so CI
was still building against an EOL protobuf release even after the
minimum version bump.
This PR updates both scripts to build `protobuf v31.1` (package version
`6.31.1`) with `abseil-cpp 20250127.0`, matching the versions already
pinned in `sbom.cdx.json`.
Signed-off-by: Andreas Fehlner <fehlner@arcor.de>
Andreas Fehlner
f2fb04c596