Fix migration file extension when publishing from Package

When Package has registered migrations to publish,
resulting migration file being published without '.php'
file extension. In order to get Migration discovered and
available to run, file should be properly named in the form
of 'Y_m_d_His_migration_file_name_here.php' and should have
'.php' extension.

Author: DmytroSeredinov

src/PackageServiceProvider.php

@@ -4,6 +4,7 @@
 namespace Spatie\LaravelPackageTools;
 
 use Illuminate\Support\ServiceProvider;
+use Illuminate\Support\Str;
 use ReflectionClass;
 use Spatie\LaravelPackageTools\Exceptions\InvalidPackage;
 
@@ -54,7 +55,7 @@ public function boot()
             foreach ($this->package->migrationFileNames as $migrationFileName) {
                 if (! $this->migrationFileExists($migrationFileName)) {
                     $this->publishes([
-                        $this->package->basePath("/../database/migrations/{$migrationFileName}.php.stub") => database_path('migrations/' . now()->format('Y_m_d_His') . '_' . $migrationFileName),
+                        $this->package->basePath("/../database/migrations/{$migrationFileName}.php.stub") => database_path('migrations/' . now()->format('Y_m_d_His') . '_' . Str::finish($migrationFileName, '.php')),
                     ], "{$this->package->name}-migrations");
                 }
             }

tests/PackageServiceProviderTests/PackageMigrationTest.php

@@ -23,6 +23,6 @@ public function it_can_publish_the_migration()
             ->artisan('vendor:publish --tag=laravel-package-tools-migrations')
             ->assertExitCode(0);
 
-        $this->assertFileExists(database_path('migrations/2020_01_01_000000_create_laravel_package_tools_table'));
+        $this->assertFileExists(database_path('migrations/2020_01_01_000000_create_laravel_package_tools_table.php'));
     }
 }