remove old jekyll versions and bump ruby version

.drone.yml

@@ -1,35 +1,13 @@
 pipeline:
 
-  jekyll-3.8:
-    image: plugins/docker
-    repo: bunix42/jekyll
-    build_args:
-      - JEKYLL_VERSION=3.8.7
-      - RUBY_VERSION=2-alpine3.13
-    tags:
-      - 3.8.7
-      - 3.8
-    secrets: [ docker_username, docker_password ]
-
-  jekyll-3.9:
-    image: plugins/docker
-    repo: bunix42/jekyll
-    build_args:
-      - JEKYLL_VERSION=3.9.1
-      - RUBY_VERSION=2-alpine3.13
-    tags:
-      - 3.9.1
-      - 3.9
-    secrets: [ docker_username, docker_password ]
-
   jekyll-4.2:
     image: plugins/docker
     repo: bunix42/jekyll
     build_args:
-      - JEKYLL_VERSION=4.2.1
+      - JEKYLL_VERSION=4.2.2
-      - RUBY_VERSION=3-alpine3.13
+      - RUBY_VERSION=3-alpine
     tags:
-      - 4.2.1
+      - 4.2.2
       - 4.2
     secrets: [ docker_username, docker_password ]