Remove obsolete NotParallelSafe flag for test_zlib (#2053)

Co-authored-by: Tiffany Elangwa <tiffanyelangwa@uni.minerva.edu>

Author: tiffanyelangwa

tests/IronPython.Tests/Cases/IronPythonCasesManifest.ini

@@ -194,7 +194,6 @@ NotParallelSafe=true # Uses a temporary module with a fixed name
 RetryCount=2
 
 [IronPython.modules.misc.test_zlib]
-NotParallelSafe=true # test_data.gz
 
 [IronPython.modules.system_related.test_nt]
 RunCondition=NOT $(IS_POSIX)