update to dune 2.1

[tcoopman]

Fixes #12

[tcoopman]

There are still some issues with esy build --release that doesn't work:

info esy build 0.6.2 (using package.json)
File "ReWebTest/HeaderTest/dune", line 3, characters 19-27:
3 |   (libraries ReWeb alcotest))
                       ^^^^^^^^
Error: Library "alcotest" not found.
Hint: try: dune external-lib-deps --missing --only-packages re-web @@default
File "ReWebTest/dune", line 4, characters 39-51:
4 |   (libraries HeaderTest ReWeb alcotest alcotest-lwt)
                                           ^^^^^^^^^^^^
Error: Library "alcotest-lwt" not found.
Hint: try: dune external-lib-deps --missing --only-packages re-web @@default
error: command failed: 'dune' 'build' '--only-packages' 're-web' (exited with 1)
esy-build-package: exiting with errors above...
error: build failed with exit code: 1

esy: exiting due to errors above

I'm looking into why that fails

[yawaramin]

Thanks Thomas. It would be great to get on dune 2. I can confirm the release-mode build works correctly on current dune i.e. 1.11.

[tcoopman]

I already asked about it on discord esy channel. But I'm not at my pc at the moment, so this will probably something for this evening

[tcoopman]

I've been able to (temporarily) fix the problem by moving the missing packages to dependencies, but when I now try to use this branch in my project it fails with Library re-web not found???

So I'm a bit stuck, going to wait for feedback on discord

[tcoopman]

In the end, with the help of @Et7f3 it has been solved and this now builds correctly with dune 2.

[yawaramin]

Thanks again!