chore: adjust code for cs-fixer no-useless-else

[phil-davis]

php-cs-fixer 3.93 (among many other things) added a fixer for no-useless-else

PHP-CS-Fixer/PHP-CS-Fixer#9340

Let php-cs-fixer get rid of these useless else blocks.

No change to behaviour, so no need to release.

[codecov]

Codecov Report

❌ Patch coverage is 85.71429% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 99.18%. Comparing base (3b64d4b) to head (26e5fbd).
⚠️ Report is 3 commits behind head on master.

Files with missing lines	Patch %	Lines
lib/Promise.php	66.66%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff            @@
##             master     #144   +/-   ##
=========================================
  Coverage     99.18%   99.18%           
  Complexity      111      111           
=========================================
  Files             7        7           
  Lines           370      370           
=========================================
  Hits            367      367           
  Misses            3        3           

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[phil-davis]

The uncovered line is in Promise wait(), the very bottom line that throws LogicException()
A LogicException thrown higher up is covered by a test that purposely uses a Promise of nothing.
The last LogicExcetion looks difficult to get that code to execute, so difficult to cover.