Update test-unit requirement from = 3.5.9 to = 3.6.1

Updates the requirements on [test-unit](https://github.com/test-unit/test-unit) to permit the latest version.
- [Release notes](https://github.com/test-unit/test-unit/releases)
- [Commits](test-unit/test-unit@3.5.9...3.6.1)

---
updated-dependencies:
- dependency-name: test-unit
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

Gemfile

@@ -12,6 +12,6 @@ gem 'rubocop', '1.54.1'
 gem 'rubocop-minitest', '0.31.0'
 gem 'rubocop-rake', '0.6.0'
 gem 'simplecov', '0.22.0'
-gem 'test-unit', '3.5.9'
+gem 'test-unit', '3.6.1'
 gem 'timecop', '0.9.6'
 gem 'yard', '0.9.34'

Gemfile.lock

@@ -54,7 +54,7 @@ GEM
       simplecov_json_formatter (~> 0.1)
     simplecov-html (0.12.3)
     simplecov_json_formatter (0.1.4)
-    test-unit (3.5.9)
+    test-unit (3.6.1)
       power_assert
     timecop (0.9.6)
     unicode-display_width (2.4.2)
@@ -72,7 +72,7 @@ DEPENDENCIES
   rubocop-minitest (= 0.31.0)
   rubocop-rake (= 0.6.0)
   simplecov (= 0.22.0)
-  test-unit (= 3.5.9)
+  test-unit (= 3.6.1)
   timecop (= 0.9.6)
   yard (= 0.9.34)