Sækja Haskell Stack 3.5.1

See https://haskellstack.org/ for installation and upgrade instructions.
Changes since v3.3.1:
Behavior changes:
- Stack will also warn (message S-8432) if there is any non-ISO/IEC 8859-1 (Latin-1) character in Stack's 'programs' path, as hsc2hs does not work if there is such a character in the path to its default template template-hsc.h.
- Stack customizes setup using Cabal, so if a setup-depends field does not mention it as a dependency, Stack warns and adds the GHC boot package as a dependency. Previously, Stack would not do so but only warn that build errors were likely.
Other enhancements:
- Bump to Hpack 0.38.0.
- In YAML configuration files, the install-msys key is introduced, to enable or disable the download and installation of Stack-supplied MSYS2 when necessary (subject to skip-msys: false). The default is the same as the install-ghc setting (including if that is set at the command line). Consequently, the default behaviour of Stack is unaffected.
- Add the stack config set install-msys command to configure the install-msys option in YAML configuration files.
- Option allow-newer-deps is no longer classified as experimental in documentation.
- stack sdist and stack upload report the version of Cabal (the library) being used to check packages.
- Add the stack config build-files command to generate (when applicable) a Cabal file from a package description in the Hpack format and/or a lock file for Stack's project-level configuration, without taking any other build steps.
Thanks to all our contributors for this release:
- Mike Pilgrem
- Olivier Benz