Consider foreign key constraints with isRelationNullable (#1231)

* Consider foreign key constraints with isRelationNullable

* test: add belongsTo Variation

* command: composer test-regenerate

tests/Console/ModelsCommand/migrations/____belongs_to_variation_table.php

@@ -0,0 +1,23 @@
+<?php
+
+declare(strict_types=1);
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+class BelongsToVariationTable extends Migration
+{
+    public function up(): void
+    {
+        Schema::create('belongs_to_variations', function (Blueprint $table) {
+            $table->bigIncrements('id');
+            $table->integer('not_null_column_with_foreign_key_constraint');
+            $table->integer('not_null_column_with_no_foreign_key_constraint');
+            $table->integer('nullable_column_with_foreign_key_constraint')->nullable();
+            $table->integer('nullable_column_with_no_foreign_key_constraint')->nullable();
+            $table->foreign('not_null_column_with_foreign_key_constraint')->references('id')->on('belongs_to_variations');
+            $table->foreign('nullable_column_with_foreign_key_constraint')->references('id')->on('belongs_to_variations');
+        });
+    }
+}