Support pnpm lockfileVersion: 5.4

[tennox]

Pnpm v7.9.5 generates lockfileVersion: 5.4, which errors:

error: assertion '(((pnpmlock).lockfileVersion == 5) || ((pnpmlock).lockfileVersion == 5.1))' failed

       at /home/manu/dev/stuff/pnpm2nix/default.nix:201:5:

          200|   in
          201|     assert (pnpmlock.lockfileVersion == 5 || pnpmlock.lockfileVersion == 5.1);

Did not find a way to tell pnpm to write with an older lockfile version

[phenax]

+1

[EndangeredMassa]

I needed to understand the breakdown of which versions of pnpm generated and parsed which versions of their lockfile for something else, then came across this post. I figured I'd share.

I tested all versions from 6+ and confirmed it with pnpm itself. The logic checking pnpm lockfile versions should accommodate these:

| pnpm version | generates lockfile | parses lockfiles |
| ------------ | ------------------ | ---------------- |
| 6.x          | 5.3                | 5.3, 5.4         |
| 7.x          | 5.4                | 5.3, 5.4         |
| 8.x          | 6.0                | 6.0, 6.1?        |
| - 8.6.1      | 6.1                | 6.0, 6.1?        |
| - 8.6.2      | 6.1                | 6.0, 6.1?        |
| - after      | 6.0                | 6.0, 6.1?        |
| 9.x          | 7.0                | 7.0, 6.1?        |

I didn't go back and test which pnpm versions can parse lockfile version 6.1, though.