Fix: Remove upper constraint for phpunit/phpunit

[localheinz]

This PR

• removes the upper version constraint for phpunit/phpunit

Follows #97.

[codecov]

Codecov Report

Merging #98 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             master    #98   +/-   ##
=======================================
  Coverage       100%   100%           
+ Complexity       64     41   -23     
=======================================
  Files             4      4           
  Lines           170    161    -9     
=======================================
- Hits            170    161    -9

Impacted Files	Coverage Δ	Complexity Δ
src/Helper.php	100% <0%> (ø)	37% <0%> (-23%)	⬇️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update e919684...c68fb9e. Read the comment docs.