Downgrades webmock and adds base64 to keep both Ruby 3.4 support and add support back for older Ruby versions

Author: torresga

next_rails.gemspec

@@ -30,5 +30,6 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency "timecop", "~> 0.9.1"
   spec.add_development_dependency "byebug"
   spec.add_development_dependency "rexml", "3.3.8" # limited on purpose, new versions don't work with old rubies
-  spec.add_development_dependency "webmock", "3.20.0"
+  spec.add_development_dependency "webmock", "3.16.2"
+  spec.add_development_dependency "base64"
 end