chore: add clippy::string_slice

[joshka]

Fixes: https://github.com/ratatui-org/ratatui/issues/1056

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 94.3%. Comparing base (4bfdc15) to head (258005a).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #1064 +/- ## ===================================== Coverage 94.3% 94.3% ===================================== Files 60 60 Lines 14679 14682 +3 ===================================== + Hits 13843 13846 +3 Misses 836 836 ```

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[joshka]

btw @EdJoPaTo I think you were right about that multiple dependencies lint.

❯ cargo tree -i windows-targets@0.48.5 --target all
windows-targets v0.48.5
├── parking_lot_core v0.9.9
│   └── parking_lot v0.12.1
│       └── crossterm v0.27.0
│           └── ratatui v0.26.2 (/Users/joshka/local/ratatui)
└── windows-sys v0.48.0
    └── mio v0.8.10
        ├── crossterm v0.27.0 (*)
        └── signal-hook-mio v0.2.3
            └── crossterm v0.27.0 (*)

❯ cargo tree -i windows-targets@0.52.5 --target all
windows-targets v0.52.5
└── windows-sys v0.52.0
    ├── console v0.15.8
    │   └── better-panic v0.3.0
    │       [dev-dependencies]
    │       └── ratatui v0.26.2 (/Users/joshka/local/ratatui)
    ├── is-terminal v0.4.12
    │   └── criterion v0.5.1
    │       [dev-dependencies]
    │       └── ratatui v0.26.2 (/Users/joshka/local/ratatui)
    └── winapi-util v0.1.8
        ├── same-file v1.0.6
        │   └── walkdir v2.5.0
        │       └── criterion v0.5.1 (*)
        └── walkdir v2.5.0 (*)

[joshka]

I think this was probably done well enough elsewhen.