Problem: we take nyan-interpolation from GitHub, which is harder
to manage than if we take it from Hackage.
Fortunately, the latest version is now available and suits us.

Solution: specify Hackage version of nyan-interpoation[-core]
in extra-deps.

Problem: this is a new warning which wants us to provide an explicit
kind signature for each type we define. It sounds too verbose to do.

Solution: disable this warning.

Problem: retryAfterInfo doesn't compile because the type of
readMaybe got more polymorphic in Universum.

Solution: specify explicitly that the argument is Text.
N.B. In the previous version it was String (due to the old type of
readMaybe), but Text is generally preferable, so we're changing it.

Problem: some lens-related things that we use got deprecated in
Universum.
Solution: do not use them, import them from Control.Lens instead.

…etty

Problem: build failure with newer versions of optparse-applicative
  Module ‘Options.Applicative.Help.Pretty’ does not export ‘displayS’
  Module ‘Options.Applicative.Help.Pretty’ does not export ‘renderPretty’
  Module ‘Options.Applicative.Help.Pretty’ does not export ‘text’

Solution: stop using functions that have been removed.

Problem: Cross-compilation to windows is broken.

Solution: Build 'bitvec' without 'simd' flag

Problem: `firefly` depends on `regex-pcre`, which fails to build in
certain configurations:

  regex-pcre > regex-pcre-0.95.0.0: library-dirs: /usr/lib is a relative path which makes no
  regex-pcre > sense (as there is nothing for it to be relative to). You can make paths
  regex-pcre > relative to the package database itself by using ${pkgroot}. (use --force to
  regex-pcre > override)
  regex-pcre > regex-pcre-0.95.0.0: dynamic-library-dirs: /usr/lib is a relative path which
  regex-pcre > makes no sense (as there is nothing for it to be relative to). You can make
  regex-pcre > paths relative to the package database itself by using ${pkgroot}. (use
  regex-pcre > --force to override)

The problem only occurs with `stack` on Windows. Therefore, there are
two possible workarounds: (a) use `cabal`, (b) drop Windows support.
However, we would like to support both build tools on all platforms if
possible.

Solution: replace `firefly` with `scotty`, a different web server
library that does not depend on `regex-pcre`.