Update zlib from 3.12.6 and _ZlibDecompressor implementation (RustPython#5476)

* add is_s390x and skip_on_s390x to test support

* update zlib tests to 3.12

* _ZlibDecompressor implementation

Author: arihant2math

Lib/test/support/__init__.py

@@ -532,6 +532,10 @@ def requires_legacy_unicode_capi():
 
 has_fork_support = hasattr(os, "fork") and not is_emscripten and not is_wasi
 
+# From python 3.12.6
+is_s390x = hasattr(os, 'uname') and os.uname().machine == 's390x'
+skip_on_s390x = unittest.skipIf(is_s390x, 'skipped on s390x')
+
 def requires_fork():
     return unittest.skipUnless(has_fork_support, "requires working os.fork()")