Add localstack to utils runtime dependencies

The utils package imports from localstack at runtime (docker.py), so it
must be a runtime dependency, not just a dev/test extra. Without this,
installing utils via git ref in CI fails with ModuleNotFoundError.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: whummer

utils/pyproject.toml

@@ -18,6 +18,7 @@ dependencies = [
     "hpack",
     "httpx",
     "hyperframe",
+    "localstack",
     "priority",
     "requests",
     "rolo",
@@ -32,15 +33,13 @@ dev = [
     "boto3",
     "build",
     "jsonpatch",
-    "localstack",
     "pytest",
     "ruff",
 ]
 test = [
     "grpcio>=1.60.0",
     "grpcio-tools>=1.60.0",
     "jsonpatch",
-    "localstack",
     "pytest>=7.0",
     "pytest-timeout>=2.0",
 ]