test/pnpm: fix fixup-state-db test by storing SQL dump

Fixup-state-db is effectively only used in fetchPnpmDeps.
We previously included the SQLite database in the FOD, it was first
problematic as it produced different hashes on linux and darwin, but
SQLite version updates have a higher chance of changing the DB format
and break our hashes, that just happened with the 3.53.1 -> 3.53.3 bump.

Nowadays fetchPnpmDeps relies on the SQL dump of the database which is
more stable, but in the past hashes were broken once.

The point is, we no longer rely on the raw DB, but only it's dump, so
it's safe to assert for that in this test.

pkgs/test/pnpm/pnpm-fixup-state-db/default.nix

@@ -16,8 +16,8 @@ testers.runCommand {
 
     pnpm-fixup-state-db ./store
 
-    cp ./store/index.db $out
+    sqlite3 ./store/index.db .dump > $out
   '';
 
-  hash = "sha256-P3PDQAziwUxl2pfYV+QyPVwNpq90Jg46bawTvrT0NOQ=";
+  hash = "sha256-PEzcJgGRo+dK5X9TBcx3A+BOIsvJ7gFmzV8vanTuGCo=";
 }