Installing Ruby 2.3.8 uses incompatible openssl

I've installed OpenSSL through homebrew, and I'm installing ruby 2.3.8 and getting the following error:
```
$ asdf install ruby 2.3.8
Downloading ruby-build...
Cloning into 'ruby-build-source'...
remote: Enumerating objects: 386, done.
remote: Counting objects: 100% (386/386), done.
remote: Compressing objects: 100% (274/274), done.
remote: Total 10645 (delta 267), reused 150 (delta 94), pack-reused 10259
Receiving objects: 100% (10645/10645), 2.24 MiB | 1.63 MiB/s, done.
Resolving deltas: 100% (6948/6948), done.
Note: checking out 'v20191102'.

You are in 'detached HEAD' state. You can look around, make experimental
changes and commit them, and you can discard any commits you make in this
state without impacting any branches by performing another checkout.

If you want to create a new branch to retain commits you create, you may
do so (now or later) by using -b with the checkout command again. Example:

git checkout -b

HEAD is now at f6e8dc1 ruby-build 20191102
ruby-build: using openssl from homebrew
Downloading ruby-2.3.8.tar.bz2...
-> https://cache.ruby-lang.org/pub/ruby/2.3/ruby-2.3.8.tar.bz2
Installing ruby-2.3.8...
ruby-build: using readline from homebrew

BUILD FAILED (OS X 10.14.6 using ruby-build 20191102)

Inspect or clean up the working tree at /var/folders/9b/922bttx934n7l9d0jf66xzn00000gn/T/ruby-build.20200219123505.39425
Results logged to /var/folders/9b/922bttx934n7l9d0jf66xzn00000gn/T/ruby-build.20200219123505.39425.log

Last 10 log lines:
installing capi-docs: /Users/dean/.asdf/installs/ruby/2.3.8/share/doc/ruby
The Ruby openssl extension was not compiled.
ERROR: Ruby install aborted due to missing extensions
Configure options used:
--prefix=/Users/dean/.asdf/installs/ruby/2.3.8
--with-openssl-dir=/usr/local/opt/openssl@1.1
--with-readline-dir=/usr/local/opt/readline
CC=clang
LDFLAGS=-L/Users/dean/.asdf/installs/ruby/2.3.8/lib
CPPFLAGS=-I/Users/dean/.asdf/installs/ruby/2.3.8/include
```
It's using the new openssl 1.1, which I think it isn't compatible with.

When using `ruby-build` directly, it downloads and uses openssl 1.0.2b and ruby install works.

Updating to head (`asdf update --head`) solved the issue. It looks like [this version bump](https://github.com/asdf-vm/asdf-ruby/blob/master/lib/utils.sh#L1) solved it.