Update minitest-parallel_fork requirement from ~> 1.3 to ~> 2.0 (#96)

Updates the requirements on [minitest-parallel_fork](https://github.com/jeremyevans/minitest-parallel_fork) to permit the latest version.
- [Changelog](https://github.com/jeremyevans/minitest-parallel_fork/blob/master/CHANGELOG)
- [Commits](jeremyevans/minitest-parallel_fork@1.3.1...2.0.0)

---
updated-dependencies:
- dependency-name: minitest-parallel_fork
  dependency-type: direct:development
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Gemfile.lock

@@ -21,7 +21,7 @@ GEM
       mime-types-data (~> 3.2015)
     mime-types-data (3.2021.0225)
     minitest (5.20.0)
-    minitest-parallel_fork (1.3.1)
+    minitest-parallel_fork (2.0.0)
       minitest (>= 5.15.0)
     netrc (0.11.0)
     public_suffix (5.0.3)
@@ -46,7 +46,7 @@ PLATFORMS
 DEPENDENCIES
   bundler (~> 2.2)
   minitest (~> 5.0)
-  minitest-parallel_fork (~> 1.3)
+  minitest-parallel_fork (~> 2.0)
   rake (~> 13.0)
   seatsio!
   webmock (~> 3.4, >= 3.4.2)

seatsio.gemspec

@@ -26,5 +26,5 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency "rake", "~> 13.0"
   spec.add_development_dependency "minitest", "~> 5.0"
   spec.add_development_dependency 'webmock', '~> 3.4', '>= 3.4.2'
-  spec.add_development_dependency 'minitest-parallel_fork', '~> 1.3'
+  spec.add_development_dependency 'minitest-parallel_fork', '~> 2.0'
 end