simplesamlphp_auth 8.x-3.0-rc1

Changes since 8.x-3.0-alpha4:

• #2859215 by rocket.man: Replace deprecated uses
• #2651192 by renatog, vomiand: Varnish causing saml_login page to go into an infinite loop between drupal, simplesamlphp and idp
• #2832549 by TravisCarden, Maesteri: Security update to Composer package: update composer.json
• #2844092 by nehakhadke: Remove @file tag docblock from all the .php files
• #2760995 by balsama: simplesamlphp dependency should use next significant release operator
• Fix logout URL in SimpleSAMLphp_auth block

Note: the update contains a security update in the composer dependency, not within in the module code.