Fix new clippy warnings (Rigellute#614)

* Fix new clippy warnings

* Temp downgrade clippy toolchain

Clippy is failing on CI with

```
panicked at 'index out of bounds: the len is 1 but the index is 1', src/tools/clippy/clippy_lints/src/repeat_once.rs:44:93
```

This has been fixed in clippy itself, but was missed in the 1.47.0
release (rust-lang/rust-clippy#6147).

Author: Rigellute

.github/workflows/ci.yml

@@ -72,9 +72,10 @@ jobs:
     needs: prepare
     steps:
       - uses: actions/checkout@master
+      # Temporarily downgrade Clippy until a new stable release includes a fix for CI breaking on 1.47 https://github.com/rust-lang/rust-clippy/issues/6147
       - uses: actions-rs/toolchain@v1
         with:
-          toolchain: stable
+          toolchain: 1.46.0
           override: true
       - run: rustup component add clippy
       - uses: actions-rs/cargo@v1

src/handlers/common_key_events.rs

@@ -1,52 +1,32 @@
 use super::super::app::{ActiveBlock, App, RouteId};
 use crate::event::Key;
+
 pub fn down_event(key: Key) -> bool {
-  match key {
-    Key::Down | Key::Char('j') | Key::Ctrl('n') => true,
-    _ => false,
-  }
+  matches!(key, Key::Down | Key::Char('j') | Key::Ctrl('n'))
 }
 
 pub fn up_event(key: Key) -> bool {
-  match key {
-    Key::Up | Key::Char('k') | Key::Ctrl('p') => true,
-    _ => false,
-  }
+  matches!(key, Key::Up | Key::Char('k') | Key::Ctrl('p'))
 }
 
 pub fn left_event(key: Key) -> bool {
-  match key {
-    Key::Left | Key::Char('h') | Key::Ctrl('b') => true,
-    _ => false,
-  }
+  matches!(key, Key::Left | Key::Char('h') | Key::Ctrl('b'))
 }
 
 pub fn right_event(key: Key) -> bool {
-  match key {
-    Key::Right | Key::Char('l') | Key::Ctrl('f') => true,
-    _ => false,
-  }
+  matches!(key, Key::Right | Key::Char('l') | Key::Ctrl('f'))
 }
 
 pub fn high_event(key: Key) -> bool {
-  match key {
-    Key::Char('H') => true,
-    _ => false,
-  }
+  matches!(key, Key::Char('H'))
 }
 
 pub fn middle_event(key: Key) -> bool {
-  match key {
-    Key::Char('M') => true,
-    _ => false,
-  }
+  matches!(key, Key::Char('M'))
 }
 
 pub fn low_event(key: Key) -> bool {
-  match key {
-    Key::Char('L') => true,
-    _ => false,
-  }
+  matches!(key, Key::Char('L'))
 }
 
 pub fn on_down_press_handler<T>(selection_data: &[T], selection_index: Option<usize>) -> usize {