fix: Explicitly require openssl gem (#334)

OpenSSL 3.6.0 introduced a change in behavior which prevents the SDK
from initializing. To learn more, refer to [this github ticket][1].

To mitigate this, we explicitly depend on the openssl gem instead of
loading the default version shipped with Ruby.

This SDK still advertises Ruby 3.1+ support, which should require a
minimum threshold of openssl-v3.0+. However, Ruby 3.1 is EOL and the
openssl maintainer only implemented fixes in openssl-v3.1+. Thus, we set
the minimum to openssl-v3.1.

[1]: ruby/openssl#949

fixes #333

Author: keelerm84

launchdarkly-server-sdk.gemspec

@@ -39,6 +39,7 @@ Gem::Specification.new do |spec|
   spec.add_runtime_dependency "concurrent-ruby", "~> 1.1"
   spec.add_runtime_dependency "ld-eventsource", "2.2.6"
   spec.add_runtime_dependency "observer", "~> 0.1.2"
+  spec.add_runtime_dependency "openssl", "~> 3.1", ">= 3.1.2"
   spec.add_runtime_dependency "semantic", "~> 1.6"
   spec.add_runtime_dependency "zlib", "~> 3.1" unless RUBY_PLATFORM == "java"
   # Please keep ld-eventsource dependency as an exact version so that bugfixes to