Feature: Support php7.4 (#1354)

* Run CI tests against php 7.4

* Sort composer dependencies

* Remove unused Aws S3 php library

* Pin simplepie dependency to ^1.5

* Pin getid3 dependency to ^1.9

* Pin composer semver to ^3.2

* Pin php-amqplib to ^2.12

* Drop sentry logging support

* Update composer dependencies

* Move propel regenerate to Makefile

* Regenerate propel files with v1.7.0

* Pin propel orm to ^1.7

* Regenerate propel files with v1.7.2

* fix: generator_version in airtime-conf-production.php

* Replace propel/propel1 with jooola/propel1

* Regenerate propel files with v1.7.3-dev

* Fix php7.4 compatibility

Using php-cs-fixer:

    '@PhpCsFixer' => true,
    'concat_space' => ['spacing' => 'one'],
    'ordered_class_elements' => false,
    'yoda_style' => false,
    '@PHP74Migration' => true,
    'assign_null_coalescing_to_coalesce_equal' => false,
    'ternary_to_null_coalescing' => false,
    'heredoc_indentation' => false,
    '@PHP74Migration:risky' => true,
    'declare_strict_types' => false,
    'void_return' => false,
    'use_arrow_functions' => false,

* Fix pre-commit

legacy/application/services/PodcastService.php

@@ -82,7 +82,7 @@ class Application_Service_PodcastService
                 array_push($categories, $category->get_scheme() . ':' . $category->get_term());
             }
         }
-        $podcastArray['category'] = htmlspecialchars(implode($categories));
+        $podcastArray['category'] = htmlspecialchars(implode('', $categories));
 
         //TODO: put in constants
         $itunesChannel = 'http://www.itunes.com/dtds/podcast-1.0.dtd';