Make filters with multiple form items work

[luisdalmolin]

Example: Date filter with month and year.

            ->filters([
                Filter::make('date_filter')
                    ->label('Date Filter')
                    ->form([
                        Select::make('month')
                            ->label('Month')
                            ->options([
                                1 => 'January',
                                2 => 'February',
                                3 => 'March',
                                4 => 'April',
                                5 => 'May',
                                6 => 'June',
                                7 => 'July',
                                8 => 'August',
                                9 => 'September',
                                10 => 'October',
                                11 => 'November',
                                12 => 'December',
                            ])
                            ->placeholder('Select Month'),
                        Select::make('year')
                            ->label('Year')
                            ->options(function () {
                                $currentYear = date('Y');
                                $years = [];
                                for ($i = $currentYear - 5; $i <= $currentYear + 1; $i++) {
                                    $years[$i] = $i;
                                }
                                return $years;
                            })
                            ->placeholder('Select Year'),
                    ])

[luisdalmolin]

Fixed in #5