Since <https://github.com/NixOS/nixpkgs/pull/109143> has been merged,
switching opam-file-format doesn't create a cyclical dependency of
opam-file-format -> dune -> opaline -> opam-file-format anymore.
Thus we switch to dune which seems to be supported better by upstream
and doesn't require us to patch the 2.1.2 release.
Insync 3.0 is a full rewrite with a different feature set than the
existing v1 derivation in nixpkgs. Some users need to stick with the
old version, particularly those on headless/non-GUI systems. There is
a headless version of v3, but that will need to be packaged separately.
###### Motivation for this change
Update to latest upstream version
###### Things done
* [ ] Tested using sandboxing ([nix.useSandbox](http://nixos.org/nixos/manual/options.html#opt-nix.useSandbox) on NixOS, or option `sandbox` in [`nix.conf`](http://nixos.org/nix/manual/#sec-conf-file) on non-NixOS linux)
* Built on platform(s)
* [x] NixOS
* [ ] macOS
* [ ] other Linux distributions
* [ ] Tested via one or more NixOS test(s) if existing and applicable for the change (look inside [nixos/tests](https://github.com/NixOS/nixpkgs/blob/master/nixos/tests))
* [ ] Tested compilation of all pkgs that depend on this change using `nix-shell -p nix-review --run "nix-review wip"`
* [x] Tested execution of all binary files (usually in `./result/bin/`)
* [ ] Determined the impact on package closure size (by running `nix path-info -S` before and after)
* [ ] Ensured that relevant documentation is up to date
* [x] Fits [CONTRIBUTING.md](https://github.com/NixOS/nixpkgs/blob/master/.github/CONTRIBUTING.md).
###### Notify maintainers
cc @blitz @Ma27 @tfc @worldofpeace
I forgot that string comparison isn't enough because e.g.:
>>> "89.0.4389.9" < "89.0.4389.23"
False
distutils.version.LooseVersion is undocumented but it works and is
already available so why not use it:
>>> LooseVersion("89.0.4389.9") < LooseVersion("89.0.4389.23")
True
