setup: reset lock file, prevents Error: Failed to install provider

error example:

```
Error while installing hashicorp/external v2.3.4: the local package for
registry.opentofu.org/hashicorp/external 2.3.4 doesn't match any of the
checksums previously recorded in the dependency lock file (this might be
because the available checksums are for packages targeting different
platforms); for more information:
https://opentofu.org/docs/language/files/dependency-lock/#checksum-verification
```

launch/default.nix

@@ -14,6 +14,7 @@ let
   inherit (pkgs) lib;
   setup = pkgs.writeScriptBin "setup" ''
     echo '${lib.strings.toJSON sources}' > .npins.json
+    rm -f .terraform.lock.hcl
     rm -rf .terraform/
     tofu init
   '';