Update phpunit/phpunit requirement from ~4.8|~9 to include ~11 (#6)

* Update phpunit/phpunit requirement from ~4.8|~9 to ^11.2.6

---
updated-dependencies:
- dependency-name: phpunit/phpunit
  dependency-type: direct:development
...

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

* Update composer.json

* Update composer.json

* Update composer.json

---------

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

Author: dependabot[bot]

composer.json

@@ -24,7 +24,7 @@
 		"php" : ">=5.3.0"
 	},
 	"require-dev": {
-		"phpunit/phpunit": "~4.8|~9"
+		"phpunit/phpunit": "~4.8|~9|~11"
 	},
 	"autoload"   : {
 		"files": ["src/array.php"]