Add ruby 2.3 and ruby 2.5 runtimes

[blijblijblij]

Issue Ref: [Issue number related to this PR or None]
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Description:

[PR Description]
Add Ruby 2.3 and Ruby 2.5 to the supported runtimes for kubeless
TODOs:

• Ready to review
• Automated Tests
• Docs

[andresmgot]

Hi @blijblijblij,

Thanks for sending this PR! Apart from the change in the Makefile, in order to test the new versions, can you edit the file kubeless-non-rbac.jsonnet at the root of the repository? There you can add the new images (that I've just build). You need to add:

diff --git a/kubeless-non-rbac.jsonnet b/kubeless-non-rbac.jsonnet
index bdfac21b..d53dfc88 100644
--- a/kubeless-non-rbac.jsonnet
+++ b/kubeless-non-rbac.jsonnet
@@ -144,11 +144,23 @@ local runtime_images ='[
     "ID": "ruby",
     "compiled": false,
     "versions": [
+      {
+        "name": "ruby23",
+        "version": "2.3",
+        "runtimeImage": "kubeless/ruby@sha256:67870b57adebc4dc749a8a19795da801da2d05fc6e8324168ac1b227bb7c77f7",
+        "initImage": "bitnami/ruby:2.3"
+      },
       {
         "name": "ruby24",
         "version": "2.4",
-        "runtimeImage": "kubeless/ruby@sha256:01665f1a32fe4fab4195af048627857aa7b100e392ae7f3e25a44bd296d6f105",
+        "runtimeImage": "kubeless/ruby@sha256:aaa9c7f3dfd4f866a527c04171c32dae2efa420d770a6af9c517771137ab4011",
         "initImage": "bitnami/ruby:2.4"
+      },
+      {
+        "name": "ruby25",
+        "version": "2.5",
+        "runtimeImage": "kubeless/ruby@sha256:577e35724996ba340ff0a18366bce99586b0be58e4d27fa3e8038f977caf1559",
+        "initImage": "bitnami/ruby:2.5"
       }
     ],
     "depName": "Gemfile",

[andresmgot]

you need to change the name of the Dockerfiles here (Dockerfile.2.3, Dockerfile.2.4, Dockerfile.2.5)

[blijblijblij]

Yes, off course, those Dockerfile references slipped my attention, thanks for pointing this out @andresmgot

[andresmgot]

Thank you for the changes @blijblijblij. Do you mind rebasing master to fix the CI?

[blijblijblij]

Been there, done that @andresmgot , all clear?!

[andresmgot]

awesome, thanks!