Drop support for Xenial, it's old and too much trouble.

.github/workflows/molecule.yml

@@ -55,8 +55,6 @@ jobs:
             tag: "latest"
           - image: "ubuntu"
             tag: "bionic"
-          - image: "ubuntu"
-            tag: "xenial"
     steps:
       - name: checkout
         uses: actions/checkout@v2

.gitlab-ci.yml

@@ -38,8 +38,6 @@ molecule:
         tag: "latest"
       - image: "ubuntu"
         tag: "bionic"
-      - image: "ubuntu"
-        tag: "xenial"
 
 galaxy:
   script:

README.md

@@ -98,7 +98,7 @@ This role has been tested on these [container images](https://hub.docker.com/u/r
 |debian|buster, bullseye|
 |fedora|all|
 |opensuse|all|
-|ubuntu|focal, bionic, xenial|
+|ubuntu|focal, bionic|
 
 The minimum version of Ansible required is 2.9, tests have been done to:
 

meta/main.yml

@@ -29,7 +29,6 @@ galaxy_info:
       versions:
         - focal
         - bionic
-        - xenial
 
   galaxy_tags:
     - grub