[ruby/json] Reject invalid number: `-` `-.1` `-e0` #628

Job	Run time
make (check, cppflags=-DVM_CHECK_MODE)	7m 59s
make (check, i686)	9m 46s
make (check, ubuntu-24.04-arm)	6m 4s
make (test-bundler-parallel, 50)	27m 7s
make (check, ubuntu-24.04)	8m 27s
make (check, --enable-shared --enable-load-relative)	7m 34s
make (check, --disable-yjit)	6m 57s
make (test-bundled-gems)	16m 34s
Ubuntu result	4s
	1h 30m 32s

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