Replace `paste` with `pastey`

[xyzzyz]

paste is no longer maintained, and as a result cargo audit doesn't like it:

1.110 Crate:     paste
1.110 Version:   1.0.15
1.110 Warning:   unmaintained
1.110 Title:     paste - no longer maintained
1.110 Date:      2024-10-07
1.110 ID:        RUSTSEC-2024-0436
1.110 URL:       https://rustsec.org/advisories/RUSTSEC-2024-0436
1.110 Dependency tree:
1.110 paste 1.0.15
1.110 └── rustls-rustcrypto 0.0.2-alpha