gems: update base64 requirement from ~> 0.2.0 to >= 0.2, < 0.4

Updates the requirements on [base64](https://github.com/ruby/base64) to permit the latest version.
- [Release notes](https://github.com/ruby/base64/releases)
- [Commits](https://github.com/ruby/base64/compare/v0.2.0...v0.3.0)

---
updated-dependencies:
- dependency-name: base64
  dependency-version: 0.3.0
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

dyndnsd.gemspec

@@ -29,7 +29,7 @@ Gem::Specification.new do |s|
 
   s.add_dependency 'async', '~> 1.31.0'
   s.add_dependency 'async-dns', '~> 1.3.0'
-  s.add_dependency 'base64', '~> 0.2.0' # needed for async
+  s.add_dependency 'base64', '>= 0.2', '< 0.4' # needed for async
   s.add_dependency 'logger', '>= 1.6', '< 1.8'
   s.add_dependency 'metriks'
   s.add_dependency 'opentelemetry-exporter-jaeger', '~> 0.22.0'