feat: Small update to concepts

Author: GeekMasher

ql/lib/codeql/bicep/Concepts.qll

@@ -13,7 +13,7 @@ abstract class PublicResource extends Resource {
 
 module Cryptography {
   abstract class WeakTlsVersion extends Resource {
-    abstract Expr getWeakTlsVersionProperty();
+    abstract StringLiteral getWeakTlsVersionProperty();
 
     /**
      *  Returns true if the resource has a weak TLS version.

ql/lib/codeql/bicep/frameworks/Microsoft/Databases.qll

@@ -241,7 +241,7 @@ module Databases {
   }
 
   class WeakDatabaseTlsVersion extends Cryptography::WeakTlsVersion instanceof DatabaseResource {
-    override Expr getWeakTlsVersionProperty() {
+    override StringLiteral getWeakTlsVersionProperty() {
       result = DatabaseResource.super.getProperties().getProperty("minimalTlsVersion")
     }
   }