fix main conditionals

tasks/main.yml

@@ -10,10 +10,10 @@
 - import_tasks: preseed.yml
 
 - import_tasks: installer.yml
-  when: debian_installer_method
+  when: not debian_installer_method == false
 
-- include: method/kexec.yml
+- import_tasks: method/kexec.yml
   when: debian_installer_method == "kexec"
 
-- include: method/iso.yml
+- import_tasks: method/iso.yml
   when: debian_installer_method == "iso"