src: fix compiler warnings in node_crypto.cc

During the time between nodejs#24234
being opened and it landing, a V8 update occurred that deprecated
several APIs. This commit fixes the following compiler warnings:

../src/node_crypto.cc:3342:11:
  warning: 'Set' is deprecated: Use maybe version

../src/node_crypto.cc:3345:13:
  warning: 'GetFunction' is deprecated: Use maybe version

PR-URL: nodejs#25205
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: Daniel Bevenius <daniel.bevenius@gmail.com>

src/node_crypto.cc

@@ -3339,10 +3339,12 @@ Local<Function> KeyObject::Initialize(Environment* env, Local<Object> target) {
                                   GetAsymmetricKeyType);
   env->SetProtoMethod(t, "export", Export);
 
-  target->Set(FIXED_ONE_BYTE_STRING(env->isolate(), "KeyObject"),
-              t->GetFunction(env->context()).ToLocalChecked());
+  auto function = t->GetFunction(env->context()).ToLocalChecked();
+  target->Set(env->context(),
+              FIXED_ONE_BYTE_STRING(env->isolate(), "KeyObject"),
+              function).FromJust();
 
-  return t->GetFunction();
+  return function;
 }
 
 Local<Object> KeyObject::Create(Environment* env,