Fix neovim upgrade - Githubissues

Standards checklist:

[x] The PR title is descriptive.
[x] The code compiles (cargo build)
[x] The code passes rustfmt (cargo fmt)
[x] The code passes clippy (cargo clippy)
[x] The code passes tests (cargo test)
[x] Optional: I have tested the code myself
- [x] I also tested that Topgrade skips the step where needed

Fix neovim upgrade (command line arguments are different from the vim's one) and fix the upgrade script when using Packer.