Fix get_func_args test for pypy3
Fix get_func_args test for pypy3

These built-in functions are exposed as methods in PyPy3.
For scrapy this does not matter as:
1) they do not work for CPython at all
2) get_func_args is checked for presense of an argument in scrapy,
   extra "self" does not matter.
But it still makes sense to leave these tests so that we know we
shouldn't use get_func_args for built-in functions/methods.

scrapy/scrapy,ArturGaspar/scrapy,ssteo/scrapy,finfish/scrapy,umrashrf/scrapy,elacuesta/scrapy,wujuguang/scrapy,elacuesta/scrapy,scrapy/scrapy,eLRuLL/scrapy,ArturGaspar/scrapy,umrashrf/scrapy,ArturGaspar/scrapy,finfish/scrapy,dangra/scrapy,umrashrf/scrapy,wujuguang/scrapy,finfish/scrapy,pablohoffman/scrapy,dangra/scrapy,pablohoffman/scrapy,pablohoffman/scrapy,starrify/scrapy,ssteo/scrapy,starrify/scrapy,eLRuLL/scrapy,kmike/scrapy,pawelmhm/scrapy,elacuesta/scrapy,kmike/scrapy,dangra/scrapy,wujuguang/scrapy,eLRuLL/scrapy,Ryezhang/scrapy,kmike/scrapy,scrapy/scrapy,starrify/scrapy,ssteo/scrapy,Ryezhang/scrapy,pawelmhm/scrapy,pawelmhm/scrapy,Ryezhang/scrapy