Fix compatibility with toml 0.6.0

`toml::from_slice` has been removed. The CHANGELOG recommends using
`toml::from_str` instead and doing the byte-to-str conversion yourself.

The `toml::toml!` macro has also changed to return the type of the
value declared within the macro body. In the change in
`helix-view/src/theme.rs` this is a `toml::map::Map` (it was a
`toml::Value` previously) allowing us to skip the match and use the
map directly.

Co-authored-by: Pascal Kuthe <pascal.kuthe@semimod.de>

helix-core/tests/indent.rs

@@ -28,8 +28,8 @@ fn test_treesitter_indent(file_name: &str, lang_scope: &str) {
 
     let mut config_file = test_dir;
     config_file.push("languages.toml");
-    let config = std::fs::read(config_file).unwrap();
+    let config = std::fs::read_to_string(config_file).unwrap();
-    let config = toml::from_slice(&config).unwrap();
+    let config = toml::from_str(&config).unwrap();
     let loader = Loader::new(config);
 
     // set runtime path so we can find the queries

helix-view/src/theme.rs

@@ -517,11 +517,9 @@ mod tests {
 
         let mut style = Style::default();
         let palette = ThemePalette::default();
-        if let Value::Table(entries) = table {
+        for (_name, value) in table {
-            for (_name, value) in entries {
             palette.parse_style(&mut style, value).unwrap();
         }
-        }
 
         assert_eq!(
             style,