Pin Cabal to 3.12.10 until upstream bug is fixed

haskell/cabal#10718 breaks the tests.

.github/workflows/build.yml

@@ -20,7 +20,8 @@ jobs:
           - { os: ubuntu-latest, ghc: 9.0.2, cabal: 3.8.1.0 }
           - { os: ubuntu-latest, ghc: 9.2.4, cabal: 3.8.1.0 }
           - { os: ubuntu-latest, ghc: 9.4.3, cabal: 3.8.1.0 }
-          - { os: ubuntu-latest, ghc: latest, cabal: latest, cabal-package-flags: +os-string, ghc-flags: -Werror=deprecations }
+          # TODO: Unpin cabal from 3.12.10 after https://github.com/haskell/cabal/issues/10718 is fixed.
+          - { os: ubuntu-latest, ghc: latest, cabal: 3.12.1.0, cabal-package-flags: +os-string, ghc-flags: -Werror=deprecations }
           - { os: windows-latest, stack: lts-15.3, stack-extra-deps: "bytestring-0.11.3.0, file-io-0.1.4, filepath-1.4.100.0, time-1.9.3, Win32-2.13.3.0", overrides: "before_prepare() { sed -i.bak -e /CreateSymbolicLinkW/d -e /GetFinalPathNameByHandleW/d configure.ac; }" }
           - { os: windows-latest, stack: lts-17.5, stack-extra-deps: "bytestring-0.11.3.0, file-io-0.1.4, filepath-1.4.100.0, time-1.9.3, Win32-2.13.3.0" }
           - { os: windows-latest, stack: lts-22.7, stack-extra-deps: "bytestring-0.11.5.3, file-io-0.1.4, filepath-1.5.2.0, os-string-2.0.2, time-1.14, Win32-2.14.0.0", stack-package-flags: "{directory: {os-string: true}, file-io: {os-string: true}, Win32: {os-string: true}}", ghc-flags: -Werror=deprecations }