Revert "nir: disable a NIR test due to undebuggable & locally unreproducible CI failures"

This reverts commit 6eb3fe2d4f.  The root cause was
a bug in Meson when using the new gtest protocol and a test failed before producing
the XML file expected by it.  This was fixed in later versions of Meson, so
we've bumped the required meson version to use that feature.  The failure should
now be properly identified, so re-enabling the NIR test.

Reviewed-by: Dylan Baker <dylan@pnwbakers.com>
Acked-by: Daniel Stone <daniels@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/14204>

src/compiler/nir/meson.build

@@ -385,7 +385,7 @@ if with_tests
         'tests/lower_returns_tests.cpp',
         'tests/negative_equal_tests.cpp',
         'tests/opt_if_tests.cpp',
-        #'tests/serialize_tests.cpp',
+        'tests/serialize_tests.cpp',
         'tests/ssa_def_bits_used_tests.cpp',
         'tests/vars_tests.cpp',
       ),