cancel running GitHub Action if a new one is created

[zmiklank]

• [x] httpd-container
• [x] nginx-container
• [x] s2i-php-container
• [x] varnish-container
• [x] mariadb-container
• [x] postgresql-container
• [x] s2i-nodejs-container
• [x] s2i-python-container
• [x] mysql-container
• [x] redis-container
• [x] s2i-perl-container
• [x] s2i-ruby-container
• [x] s2i-base-container