Bugfix/php8.1 deprecations

[acelaya]

Closes #16

[codecov-commenter]

Codecov Report

Merging #19 (a50256d) into master (c99ea91) will increase coverage by 0.19%.
The diff coverage is 100.00%.

@@             Coverage Diff              @@
##             master      #19      +/-   ##
============================================
+ Coverage     96.77%   96.96%   +0.19%     
- Complexity       37       39       +2     
============================================
  Files             2        2              
  Lines            62       66       +4     
============================================
+ Hits             60       64       +4     
  Misses            2        2              

Impacted Files	Coverage Δ
src/Shortid.php	100.00% <100.00%> (ø)

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[garak]

Thank you!

[acelaya]

Thanks!