community/php83: disable 2 serialization tests for s390x

ref https://github.com/php/php-src/issues/16528

CI can't catch it https://gitlab.alpinelinux.org/alpine/aports/-/jobs/1567439

but on builder https://github.com/php/php-src/issues/15168

TEST 8148/17152 [ext/json/tests/gh15168.phpt]
========DIFF========
     bool(false)
     int(1)
     string(28) "Maximum stack depth exceeded"
+ 
+ Termsig=0
========DONE========
[1;31mFAIL[0m GH-15168 (stack overflow in json_encode()) [ext/json/tests/gh15168.phpt] 

and another one https://github.com/php/php-src/issues/15169

TEST 15215/17151 [ext/standard/tests/serialize/gh15169.phpt]
========DIFF========
     Maximum call stack size reached. Infinite recursion?
[1;32m002+ [0m
[1;32m003+ Termsig=0[0m
========DONE========
[1;31mFAIL[0m GH-15169 (stack overflow when var serialization in ext/standard/var) [ext/standard/tests/serialize/gh15169.phpt]