Correct options key passed to ParallelTests.determine_multiple (#1018)

The --multiply-processes CLI option is being parsed into options[:multiply-processes] but the call to determine_multiple was looking for it in options[:multiply].

Author: salimepoint

CHANGELOG.md

@@ -10,6 +10,8 @@ only add here if you are working on a PR
 
 ### Fixed
 
+- The `--multiply-processes` option was being parsed into `options[:multiply-processes]` but was being referenced as `options[:multiply]` in the code 
+
 ## 5.3.0 - 2025-05-30
 
 ### Added

lib/parallel_tests/cli.rb

@@ -15,7 +15,7 @@ def run(argv)
       ENV['DISABLE_SPRING'] ||= '1'
 
       num_processes = ParallelTests.determine_number_of_processes(options[:count])
-      num_processes = (num_processes * ParallelTests.determine_multiple(options[:multiply])).round
+      num_processes = (num_processes * ParallelTests.determine_multiple(options[:multiply_processes])).round
 
       options[:first_is_1] ||= first_is_1?