fix(a11y): add h1 heading to classic challenges (#45031)

client/src/templates/Challenges/components/__snapshots__/challenge-title.test.tsx.snap

@@ -39,9 +39,9 @@ exports[`<ChallengeTitle/> renders correctly 1`] = `
     <div
       className="title-text"
     >
-      <b>
+      <h1>
         title text
-      </b>
+      </h1>
       <svg
         aria-label="icons.passed"
         height="50"

client/src/templates/Challenges/components/challenge-title.css

@@ -91,6 +91,13 @@
   padding: 0px 3px;
 }
 
+.title-text h1 {
+  font-size: inherit;
+  line-height: 1.42857143;
+  margin: 0;
+  display: inline;
+}
+
 .title-translation-cta {
   display: flex;
   flex-direction: row;

client/src/templates/Challenges/components/challenge-title.tsx

@@ -39,7 +39,7 @@ function ChallengeTitle({
       {showBreadCrumbs && <BreadCrumb block={block} superBlock={superBlock} />}
       <div className='challenge-title'>
         <div className='title-text'>
-          <b>{children}</b>
+          <h1>{children}</h1>
           {isCompleted ? (
             <GreenPass
               style={{ height: '15px', width: '15px', marginLeft: '7px' }}