Bump Cabal submodule: fix tarball extraction TOCTOU race

[angerman]

Summary

• Bumps the Cabal submodule by 1 commit to pick up the tarball extraction race fix
• Fixes intermittent "No cabal file found" errors on FreeBSD CI (and potentially other platforms)

Root Cause

When two stages of the same package (build: and host: in cross-compilation) are scheduled concurrently by InstallPlan.execute, both call withTarballLocalDirectory which:

1. Checks if distUnpackedSrcDirectory pkgid exists (keyed only by PackageId, not stage)
2. Both threads see it as non-existent
3. Both race to extract the tarball to the same directory
4. The second extraction overwrites the first mid-flight, corrupting the result

Fix

The Cabal-side fix (stable-haskell/cabal#269) adds an unpackLock to serialise the doesDirectoryExist check and unpackPackageTarball call, using the same Lock/criticalSection pattern already used for registerLock and cacheLock.

Test plan

• FreeBSD CI passes without "No cabal file found" errors
• All other CI platforms pass (no regression from the lock)