picosoc-simpleuart: remove nextpnr-xilinx-fasm2bels from required tests
picosoc-simpleuart: remove nextpnr-xilinx-fasm2bels from required tests

Signed-off-by: Alessandro Comodi <622632e70fd6771cf2cd943f69e5e51ab66adef8@antmicro.com>

SymbiFlow/fpga-tool-perf,SymbiFlow/fpga-tool-perf,SymbiFlow/fpga-tool-perf,SymbiFlow/fpga-tool-perf