Replace backtick with single quote

This changes the error message from
failed to load class `java.nio.file.Path'
to
failed to load class 'java.nio.file.Path'

Author: Owen

jbmc/src/java_bytecode/java_class_loader.cpp

@@ -176,7 +176,7 @@ java_class_loadert::get_parse_tree(
     return parse_trees;
 
   // Not found or failed to load
-  warning() << "failed to load class `" << class_name << '\'' << eom;
+  warning() << "failed to load class \'" << class_name << '\'' << eom;
   parse_trees.emplace_back(class_name);
   return parse_trees;
 }