add unit test with multiple casing

Author: duncanista

src/field_attributes.rs

@@ -601,6 +601,14 @@ wrap_option_number_from_string_fn!(
 /// let a: MyStruct = serde_json::from_str(s).unwrap();
 /// assert!(!a.boolean);
 ///
+/// /// let s = r#"{ "boolean": "TruE" }"#;
+/// let a: MyStruct = serde_json::from_str(s).unwrap();
+/// assert!(a.boolean);
+///
+/// let s = r#"{ "boolean": "fAlsE" }"#;
+/// let a: MyStruct = serde_json::from_str(s).unwrap();
+/// assert!(!a.boolean);
+///
 /// let s = r#"{ "boolean": "true" }"#;
 /// let a: MyStruct = serde_json::from_str(s).unwrap();
 /// assert!(a.boolean);