Repository: box-project/box (php)

Issue:
Docker support with PHP 8
As latest version 3.16.0, Box is supposed to support both PHP 7.x and 8.x

But when you look inside [DockerFileGenerator](https://github.com/box-project/box/blob/3.16.0/src/DockerFileGenerator.php#L43-L49) no images are defined for PHP 8.0 and 8.1

Is it just forgotten ? `8.0-cli-alpine` and `8.1-cli-alpine` images are available on DockerHub

Pull request description:
Add PHP 8.0 and 8.1 to DockerFileGenerator
Closes #630

Patch:
diff --git a/src/DockerFileGenerator.php b/src/DockerFileGenerator.php
index e4a82edb..863ad7af 100644
--- a/src/DockerFileGenerator.php
+++ b/src/DockerFileGenerator.php
@@ -41,6 +41,8 @@ final class DockerFileGenerator
         Dockerfile;
 
     private const PHP_DOCKER_IMAGES = [
+        '8.1.0' => '8.1-cli-alpine',
+        '8.0.0' => '8.0-cli-alpine',
         '7.4.0' => '7.4-cli-alpine',
         '7.3.0' => '7.3-cli-alpine',
         '7.2.0' => '7.2-cli-alpine',


Test patch:
diff --git a/tests/DockerFileGeneratorTest.php b/tests/DockerFileGeneratorTest.php
index a7211a4c..fadd6213 100644
--- a/tests/DockerFileGeneratorTest.php
+++ b/tests/DockerFileGeneratorTest.php
@@ -66,7 +66,7 @@ class DockerFileGeneratorTest extends TestCase
             ;
         } catch (UnexpectedValueException $exception) {
             $this->assertSame(
-                'Could not find a suitable Docker base image for the PHP constraint(s) "^5.3". Images available: "7.4-cli-alpine", "7.3-cli-alpine", "7.2-cli-alpine", "7.1-cli-alpine", "7-cli-alpine"',
+                'Could not find a suitable Docker base image for the PHP constraint(s) "^5.3". Images available: "8.1-cli-alpine", "8.0-cli-alpine", "7.4-cli-alpine", "7.3-cli-alpine", "7.2-cli-alpine", "7.1-cli-alpine", "7-cli-alpine"',
                 $exception->getMessage(),
             );
         }