curl errors with reject future index states test

I've noticed more than one [failure](https://github.com/haskell/cabal/actions/runs/7231693710/job/19705138391?pr=9510) of `RejectFutureIndexStates/cabal.test.hs` for `Validate ubuntu-latest ghc-8.6.5` with a curl error:

```
-----BEGIN CABAL OUTPUT-----
Warning: Caught exception during _mirrors lookup:DnsNoData
-----END CABAL OUTPUT-----
-----BEGIN CABAL OUTPUT-----
Warning: No mirrors found for http://localhost:8000/
-----END CABAL OUTPUT-----
Selected mirror http://localhost:8000/
Downloading root
Running: /usr/bin/curl 'http://localhost:8000/root.json' --output /tmp/transportAdapterGet224304-2 --location --write-out '%{http_code}' --user-agent 'cabal-install/3.11.0.0 (linux; x86_64)' --silent --show-error --dump-header /tmp/curl-headers224304-3.txt
Waiting to acquire cache lock on /home/runner/work/cabal/cabal/cabal-testsuite/PackageTests/NewUpdate/RejectFutureIndexStates/cabal.dist/home/.cabal/packages/repository.localhost/hackage-security-lock
Acquired cache lock on /home/runner/work/cabal/cabal/cabal-testsuite/PackageTests/NewUpdate/RejectFutureIndexStates/cabal.dist/home/.cabal/packages/repository.localhost/hackage-security-lock
Released cache lock on /home/runner/work/cabal/cabal/cabal-testsuite/PackageTests/NewUpdate/RejectFutureIndexStates/cabal.dist/home/.cabal/packages/repository.localhost/hackage-security-lock
-----BEGIN CABAL OUTPUT-----
Downloading the latest package list from repository.localhost
-----END CABAL OUTPUT-----
Selected mirror http://localhost:8000/
Downloading timestamp
Running: /usr/bin/curl 'http://localhost:8000/timestamp.json' --output /tmp/transportAdapterGet224304-5 --location --write-out '%{http_code}' --user-agent 'cabal-install/3.11.0.0 (linux; x86_64)' --silent --show-error --dump-header /tmp/curl-headers224304-6.txt
Downloading snapshot
Running: /usr/bin/curl 'http://localhost:8000/snapshot.json' --output /tmp/transportAdapterGet224304-8 --location --write-out '%{http_code}' --user-agent 'cabal-install/3.11.0.0 (linux; x86_64)' --silent --show-error --dump-header /tmp/curl-headers224304-9.txt
Downloading mirrors
Running: /usr/bin/curl 'http://localhost:8000/mirrors.json' --output /tmp/transportAdapterGet224304-11 --location --write-out '%{http_code}' --user-agent 'cabal-install/3.11.0.0 (linux; x86_64)' --silent --show-error --dump-header /tmp/curl-headers224304-12.txt
dieVerbatim: user error (CallStack (from HasCallStack):
withMetadata, called at src/Distribution/Simple/Utils.hs:439:12 in Cabal-3.11.0.0-inplace:Distribution.Simple.Utils
-----BEGIN CABAL OUTPUT-----
Error: cabal: '/usr/bin/curl' exited with an error:
curl: (56) Recv failure: Connection reset by peer
-----END CABAL OUTPUT-----
```