fix: remove unnecessary type assertion flagged by ESLint

Co-authored-by: NullVoxPopuli <[email protected]>
Agent-Logs-Url: https://github.com/emberjs/ember.js/sessions/12601690-6983-4ec3-a0c4-004709f37c25

Author: Copilot

packages/@glimmer/compiler/lib/passes/1-normalization/visitors/statements.ts

@@ -96,7 +96,7 @@ class NormalizationStatements {
       );
 
       if (shadowrootmodeAttr && ASTv2.isLiteral(shadowrootmodeAttr.value, 'string')) {
-        const mode = shadowrootmodeAttr.value.value as string;
+        const mode = shadowrootmodeAttr.value.value;
 
         if (mode === 'open' || mode === 'closed') {
           return this.visitList(element.body, state).mapOk(