feat: completed solutions

exercises/quizzes/quiz3.rs

@@ -10,16 +10,17 @@
 //
 // Make the necessary code changes in the struct `ReportCard` and the impl
 // block to support alphabetical report cards in addition to numerical ones.
+use std::fmt::Display;
 
 // TODO: Adjust the struct as described above.
-struct ReportCard {
-    grade: f32,
+struct ReportCard<G: Display> {
+    grade: G,
     student_name: String,
     student_age: u8,
 }
 
 // TODO: Adjust the impl block as described above.
-impl ReportCard {
+impl<G: Display> ReportCard<G> {
     fn print(&self) -> String {
         format!(
             "{} ({}) - achieved a grade of {}",