* Avoid templating GitHub Actions workflow

GitHub Actions workflow have sufficient power to express what we need.
We don't need to maintain and additional templating solution on top.

* Add GHC 9.2, bump bounds, fix syntax

* Switch to official haskell image

* Always run cli tests for ghc 8.2 and above

* Remove step to regenerate GitHub Actions workflows

* Fix missed reference to GHC version

* Fix yaml syntax

* Fix type in the GHC version

* More CI changes

- Run bootstrap.yml on ubuntu-latest
- Use explicit matrix for linux.yml
- Drop containers in favour of haskell setup action
- Drop workaround for ancient git

* Remove unneeded package from CI setup

I belive this is only necessary to run `cabal man` which we do not in
the CI.

* Drop old GHCs from the CI

* Switch macos.yml to haskell/action/setup

Also add the same GHC versions as Linux.

* Simplify CI

- Remove cabal-plan, we actually never call it (I think)
- Remove vendored cabal-doctest
- Remove few stray allow-newer clauses no longer necessary, apparently

Originally done by @gbaz in PR #7907.

* Mark GHC 9.2.1 as experimental

* Remove reference to cabal-plan from validate.sh

* setup-haskell action already runs cabal update

* Add missing build matrix in test-windows-dogfood

* Replace cabal-plan list-bin with cabal list-bin

* Enable caching in the CI

* Fix typo

* Remove continue-on-error until I figure it out

* Keep naming consistent

* Temporarily disable 8.0.2 on macos

* Add missing step id

* Tweaks

Remove workaround for nektos/act, it accidentally sneaked in.

* More tweaks

* Tweaks

* Restore cabal-plan, temporarily mark everything experimental

cabal list-bin doesn't seem to work like cabal-plan does.

* Tweaks

* Ensure cabal-plan executable gets built

* Install automake on MacOS

* Tweaks

* Tweaks

Link experimental flags to relative GitHub issues

* Fix typo

on @hasufell 's advice.

- regenerate bootstrap plans
- update CI and docker images for 8.8.4 and 8.10.4

* Changes needed for GenValidate and release.py to
  accommmodate new solver dependency
* Bumps bootstrap plans to modern GHC versions
* Update `validate.sh` and `release.py` to accommodate new solver dep.
* Update `Makefile` targets

This is based on / similar to https://github.com/haskell/cabal/pull/7219

We used import qualified M in Paths_*.hs, which might be disallowed in
GHC 8.10 when -Wprepositive-qualified-module is set.

I want to use stack diffs (https://github.com/ezyang/ghstack/

) to
submit PRs to Cabal.  Stack diffs, simply by virtue of what they
are, are PRs that are targeted to branches that are not master (they
target an appropriate base that lets GitHub render only the change
in question, even if there are other changes below it.)  However,
I don't get CI jobs on those stack diffs because the current
pull_request branch selector is too restrictive.  This PR makes
it less restrictive.

This PR is submitted using ghstack to validate that this indeed
works.

Signed-off-by: Edward Z. Yang <ezyang@fb.com>

ghstack-source-id: b135ea67848f873fc6b50b950405859587ae8d89
Pull Request resolved: https://github.com/haskell/cabal/pull/7308

8.6 was no longer included in the image

Otherwise enabling `-Wmissing-safe-haskell-mode`
would cause annoying warnings.

The are various motivation points:
- I'm not aware anyone third party running Cabal tests (maybe nixpkgs?)
- No need to do gen-extra-source-files, as Cabal-tests is not distributed
- No multiple rebuilds of Cabal-QuickCheck, Cabal-tree-diff
- Slightly smaller Cabal sdist (which is quite big still)

A script essentially runs `v2-install cabal-install:exe:cabal`,
but does some simple setup, so the result is less luckily
to be influences by environment.

Also improve bootstrap to do out-of-tree builds.
- Use http, https tricky in some environments

The folder contains also `Lexer.x`, which isn't a template as such,
but it's not far from that, conceptually. `templates/` is better
name than `boot/`