Only require dotenv in test env

with commit d3a7239 dotenv became an inherited and implicit hard dependency for any project depending on blockfrost-ruby.

Since dotenv is only needed within the test environment, moving it into `spec_helper` releases the dependency for projects depending on blockfrost-ruby and makes sure it only gets required in this library's test environment.

Author: robinboening

lib/blockfrost-ruby.rb

@@ -5,8 +5,6 @@
 # require 'blockfrost-ruby'
 # blockfrost = Blockfrostruby::CardanoMainNet.new()
 
-require 'dotenv/load'
-
 require_relative 'blockfrostruby/version'
 require_relative 'blockfrostruby/constants'
 require_relative 'blockfrostruby/configuration'

spec/spec_helper.rb

@@ -1,5 +1,6 @@
 # frozen_string_literal: true
 
+require 'dotenv/load'
 require 'blockfrost-ruby'
 
 RSpec.configure do |config|