pkgr: remove debian-8 and ubuntu-14.04 (#6853)

[skip ci]

.pkgr.yml

@@ -1,18 +1,14 @@
 targets:
-  debian-8: &debian
+  debian-9: &debian
     build_dependencies:
       - libpam0g-dev
     dependencies:
       - libpam0g
       - git
-  debian-9:
-    <<: *debian
   debian-10:
     <<: *debian
   debian-11:
     <<: *debian
-  ubuntu-14.04:
-    <<: *debian
   ubuntu-16.04:
     <<: *debian
     build_dependencies: