`mypy>=1.18` causes `autoscaling` typecheck to hang

[pcrespov]

When upgrading tool requirements in #8435, the autoscaling CI pipeline started hanging during the typecheck step.

Steps to Reproduce:

cd services/autoscaling
make install-dev
make mypy   # <-- hangs

Findings:

• The hang occurs with mypy>=1.18.
• Pinning to mypy<=1.18 (currently 1.17.1) avoids the issue.
• Tried make mypy-debug but was unable to identify the root cause.

Workaround:
constrained mypy to <=1.18 in _tools.in.

[sanderegg]

fixed by #8517