Compatibility with Webform ^6

Problem/Motivation

The Webform Jira integration requires "drupal/webform": "^5.11" which is incompatible with Drupal 9.
If the Webform ^6 is installed, the Webform Jira integration module cannot be installed.

Your requirements could not be resolved to an installable set of packages.

  Problem 1
    - drupal/webform_jira[1.0.0-alpha1, ..., 1.0.0-alpha2] require drupal/webform ^5.11 -> found drupal/webform[dev-5.x, 5.11.0, ..., 5.x-dev (alias of dev-5.x)] but it conflicts with your root composer.json require (^6.0).
    - Root composer.json requires drupal/webform_jira ^1.0@alpha -> satisfiable by drupal/webform_jira[1.0.0-alpha1, 1.0.0-alpha2].

Steps to reproduce

- Install the latest Webform with composer: composer require 'drupal/webform:^6.0'
- Try to install the Webform Jira integration with composer: composer require 'drupal/webform_jira:^1.0@alpha'

Proposed resolution

The Webform Jira integration module can be installed with Webform ^6.