Replace ApiVersion's impl with derive

- Replace the "Default" `impl` with a `#[derive()]` in config/general
- That's simpler, no extra functions

owm_widg_config/src/general.rs

@@ -2,9 +2,10 @@ use serde::Deserialize;
 
 const DEFAULT_CACHE_FILE: &str = "~/.cache/candydesktop/owm_widget.json";
 
-#[derive(Debug, Deserialize, PartialEq)]
+#[derive(Debug, Deserialize, PartialEq, Default)]
 pub enum ApiVersion {
     #[serde(rename = "free_2.5")]
+    #[default]
     Free25,
     #[serde(rename = "onecall_3.0")]
     OneCall30,
@@ -12,12 +13,6 @@ pub enum ApiVersion {
     // ...
 }
 
-impl Default for ApiVersion {
-    fn default() -> Self {
-        Self::Free25
-    }
-}
-
 fn default_api_version() -> ApiVersion {
     ApiVersion::default()
 }